Funny 18Th Birthday Shirts

Unethical Threads presents our funny 18th birthday shirts collection - where offensive meets fashionable. Each design delivers laughs and premium comfort. Shop funny 18th birthday shirts today - sizes S-4XL, 30-day satisfaction guarantee.

✓ Free Shipping On All Orders | ✓ 30-Day Guarantee | ✓ Sizes S-4XL

About Our Funny 18Th Birthday Shirts Collection

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Related Collections: Complete Funny Shirts Collection | Funny 40Th Birthday Shirts | Funny 21St Birthday T Shirts

  • Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Nothing About Me Is Flat Earth Society Meme Shirt T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers.

    *NEW* Nothing About Me Is Flat Earth Tee

    *NEW* Nothing About Me Is Flat Earth Tee

    From $24.99 USD
    From $24.99 USD
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    Size
  • text reads “I’m Stupid” in a bold, rounded font on a white shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a white shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a white shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a white shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a white shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a white shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a Black shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a Black shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a Black shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a Black shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a Black shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a Black shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a Black shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit. text reads “I’m Stupid” in a bold, rounded font on a white shirt, made to pair with the matching “I’m Fucking Stupid” tee for a wild couples gag outfit.

    I'm Stupid Tee

    I'm Stupid Tee

    From $24.99 USD
    From $24.99 USD
    Color
    Size
  • Graphic T-shirt featuring the phrase “Sid On My Face” with a bold, chaotic design inspired by a Pixar parody. The layout uses edgy humor and adult-themed wordplay. Graphic T-shirt featuring the phrase “Sid On My Face” with a bold, chaotic design inspired by a Pixar parody. The layout uses edgy humor and adult-themed wordplay. Graphic T-shirt featuring the phrase “Sid On My Face” with a bold, chaotic design inspired by a Pixar parody. The layout uses edgy humor and adult-themed wordplay. Graphic T-shirt featuring the phrase “Sid On My Face” with a bold, chaotic design inspired by a Pixar parody. The layout uses edgy humor and adult-themed wordplay. Graphic T-shirt featuring the phrase “Sid On My Face” with a bold, chaotic design inspired by a Pixar parody. The layout uses edgy humor and adult-themed wordplay. Graphic T-shirt featuring the phrase “Sid On My Face” with a bold, chaotic design inspired by a Pixar parody. The layout uses edgy humor and adult-themed wordplay. Graphic T-shirt featuring the phrase “Sid On My Face” with a bold, chaotic design inspired by a Pixar parody. The layout uses edgy humor and adult-themed wordplay.

    *NEW* Sid On My Face Tee

    *NEW* Sid On My Face Tee

    From $24.99 USD
    From $24.99 USD
    Color
    Size
  • Funny Rubik’s Cube shirt with the phrase “The More You Play With It The Harder It Gets,” combining nerd humor and inappropriate innuendo for gamers and puzzle lovers. Funny Rubik’s Cube shirt with the phrase “The More You Play With It The Harder It Gets,” combining nerd humor and inappropriate innuendo for gamers and puzzle lovers. Funny Rubik’s Cube shirt with the phrase “The More You Play With It The Harder It Gets,” combining nerd humor and inappropriate innuendo for gamers and puzzle lovers. Funny Rubik’s Cube shirt with the phrase “The More You Play With It The Harder It Gets,” combining nerd humor and inappropriate innuendo for gamers and puzzle lovers. Funny Rubik’s Cube shirt with the phrase “The More You Play With It The Harder It Gets,” combining nerd humor and inappropriate innuendo for gamers and puzzle lovers. Funny Rubik’s Cube shirt with the phrase “The More You Play With It The Harder It Gets,” combining nerd humor and inappropriate innuendo for gamers and puzzle lovers. Funny Rubik’s Cube shirt with the phrase “The More You Play With It The Harder It Gets,” combining nerd humor and inappropriate innuendo for gamers and puzzle lovers.

    *NEW* The More You Play With It Rubix Cube Tee

    *NEW* The More You Play With It Rubix Cube Tee

    From $24.99 USD
    From $24.99 USD
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    Size
  • Inappropriate pickup line shirt that says “Are You From Japan? Cuz I Wanna Get In Your Japanties.” Inappropriate pickup line shirt that says “Are You From Japan? Cuz I Wanna Get In Your Japanties.” Inappropriate pickup line shirt that says “Are You From Japan? Cuz I Wanna Get In Your Japanties.” Inappropriate pickup line shirt that says “Are You From Japan? Cuz I Wanna Get In Your Japanties.” Inappropriate pickup line shirt that says “Are You From Japan? Cuz I Wanna Get In Your Japanties.” Inappropriate pickup line shirt that says “Are You From Japan? Cuz I Wanna Get In Your Japanties.” Funny Are You From Japan Cause I'm Trying To Get In Japanties T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Are You From Japan Cause I'm Trying To Get In Japanties T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Are You From Japan Cause I'm Trying To Get In Japanties T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Are You From Japan Cause I'm Trying To Get In Japanties T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Are You From Japan Cause I'm Trying To Get In Japanties T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Are You From Japan Cause I'm Trying To Get In Japanties T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Are You From Japan Cause I'm Trying To Get In Japanties T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Inappropriate pickup line shirt that says “Are You From Japan? Cuz I Wanna Get In Your Japanties.”

    *NEW* Are You From Japan - Japanties Tee

    *NEW* Are You From Japan - Japanties Tee

    From $24.99 USD
    From $24.99 USD
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    Size
  • Weird and inappropriate funny trucker hat for men with bold white text that says “I Eat Drywall” — a top-selling crazy hat with mesh back, perfect for fans of hilarious hat sayings, unhinged humor, and funny mesh hats.

    I Eat Drywall Hat

    I Eat Drywall Hat

    $29.99 USD
    $29.99 USD
  • text reads “I Blow Bubbles” in a rounded, bold font on a black shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a black shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a black shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a black shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a black shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a black shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a white shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a white shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a white shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a white shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a white shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a white shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a white shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit. text reads “I Blow Bubbles” in a rounded, bold font on a black shirt, meant to pair with the matching “I'm Bubbles” tee for a humorous and risqué couples outfit.

    I Love To Blow Bubbles Tee

    I Love To Blow Bubbles Tee

    From $24.99 USD
    From $24.99 USD
    Color
    Size
  • Funny Tylenol Powered Fuck Machine T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Tylenol Powered Fuck Machine T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Tylenol Powered Fuck Machine T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Tylenol Powered Fuck Machine T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Tylenol Powered Fuck Machine T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Tylenol Powered Fuck Machine T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers. Funny Tylenol Powered Fuck Machine T-Shirt featuring adult humor and meme-inspired design, perfect for casual wear and humor lovers.

    Tylenol Powered Fuck Machine Tee

    Tylenol Powered Fuck Machine Tee

    From $24.99 USD
    From $24.99 USD
    Color
    Size
  • Inappropriate funny mesh trucker hat with bold black text that says “Working Hard Hardly Working Hard While Working” — a hilarious hat for men who love innuendos, dirty humor, and wearing something outrageous to work or parties. Inappropriate funny mesh trucker hat with bold black text that says “Working Hard Hardly Working Hard While Working” — a hilarious hat for men who love innuendos, dirty humor, and wearing something outrageous to work or parties. Inappropriate funny mesh trucker hat with bold black text that says “Working Hard Hardly Working Hard While Working” — a hilarious hat for men who love innuendos, dirty humor, and wearing something outrageous to work or parties.

    Working Hard Hardly Working Hard While Working Hat

    Working Hard Hardly Working Hard While Working Hat

    $29.99 USD
    $29.99 USD
    Color
  • White t-shirt with 'JEW-JITSU' graphic featuring a person in a black outfit and Star of David on a white background. White t-shirt with 'JEW-JITSU' graphic featuring a person in a black outfit and Star of David on a white background. White t-shirt with 'JEW-JITSU' graphic featuring a person in a black outfit and Star of David on a white background. White t-shirt with 'JEW-JITSU' graphic featuring a person in a black outfit and Star of David on a white background. White t-shirt with 'JEW-JITSU' graphic featuring a person in a black outfit and Star of David on a white background. White t-shirt with 'JEW-JITSU' graphic featuring a person in a black outfit and Star of David on a white background. Funny Jew Jitsu T-Shirt featuring Jewish humor and a BJJ Ju Jitsu meme-inspired design, perfect for casual wear and humor lovers. Funny Jew Jitsu T-Shirt featuring Jewish humor and a BJJ Ju Jitsu meme-inspired design, perfect for casual wear and humor lovers. Funny Jew Jitsu T-Shirt featuring Jewish humor and a BJJ Ju Jitsu meme-inspired design, perfect for casual wear and humor lovers. Funny Jew Jitsu T-Shirt featuring Jewish humor and a BJJ Ju Jitsu meme-inspired design, perfect for casual wear and humor lovers. Funny Jew Jitsu T-Shirt featuring Jewish humor and a BJJ Ju Jitsu meme-inspired design, perfect for casual wear and humor lovers. Funny Jew Jitsu T-Shirt featuring Jewish humor and a BJJ Ju Jitsu meme-inspired design, perfect for casual wear and humor lovers. Funny Jew Jitsu T-Shirt featuring Jewish humor and a BJJ Ju Jitsu meme-inspired design, perfect for casual wear and humor lovers. White t-shirt with 'JEW-JITSU' graphic featuring a person in a black outfit and Star of David on a white background.

    Jew Jitsu Tee

    Jew Jitsu Tee

    From $24.99 USD
    From $24.99 USD
    Color
    Size
  • Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.
 Funny Sir Racha Sriracha T-Shirt featuring medieval humor and meme-inspired design, perfect for casual wear and humor lovers.


    *NEW* Sir Racha Sriracha Medieval Tee

    *NEW* Sir Racha Sriracha Medieval Tee

    From $24.99 USD
    From $24.99 USD
    Color
    Size
  • Funny You Can't Spell Autism Without U+I T-Shirt featuring autism humor and meme-inspired design, perfect for casual wear and humor lovers. Funny You Can't Spell Autism Without U+I T-Shirt featuring autism humor and meme-inspired design, perfect for casual wear and humor lovers. Funny You Can't Spell Autism Without U+I T-Shirt featuring autism humor and meme-inspired design, perfect for casual wear and humor lovers. Funny You Can't Spell Autism Without U+I T-Shirt featuring autism humor and meme-inspired design, perfect for casual wear and humor lovers. Funny You Can't Spell Autism Without U+I T-Shirt featuring autism humor and meme-inspired design, perfect for casual wear and humor lovers. Funny You Can't Spell Autism Without U+I T-Shirt featuring autism humor and meme-inspired design, perfect for casual wear and humor lovers. Funny You Can't Spell Autism Without U+I T-Shirt featuring autism humor and meme-inspired design, perfect for casual wear and humor lovers.

    *NEW* You Can't Spell Autism Without U+I Tee

    *NEW* You Can't Spell Autism Without U+I Tee

    From $24.99 USD
    From $24.99 USD
    Color
    Size