A common belief held by many was that physical contact with an amphibious creature, such as frogs or toads, will result in one growing warts. However, this has proven to be merely an urban legend or myth. Despite this, the Muppets have used this concept as a joke on several occasions.
- In The Frog Prince, Taminella Grinderfall catches Princess Melora and Robin the Frog about to kiss. She interrupts them with "Don't kiss frogs, you'll get warts on your lips!" (Kermit, listening nearby, remarks, "Blasphemy!")
- On a 1974 appearance on The Tonight Show, Johnny Carson asks Kermit the Frog if he takes any personal offense when people bring up this rumor. Kermit claims to have never heard of it before and remarks, "I've caused dandruff every now and then...maybe a sore throat, but never, uh, warts."
- In a promo for episode 112 of The Muppet Show, Fozzie Bear tickles Kermit. He notes how slimy the frog is and exits, disgusted. Kermit shouts back, "Give ya' warts!"
- As Kermit meets Irving Bizarre, Fozzie's agent, in episode 122 of The Muppet Show, he cracks many jokes about his small stature and the types of clients he handles. Irving snaps that he wouldn't handle Kermit; he'd get warts.
- In episode 207 of The Muppet Show, Edgar Bergen asks about the difference between toads and frogs. Kermit claims that frogs are "handsome, debonair and charming, while toads are ugly and give you warts."
- The most notable reference to this trope is in The Muppet Movie, where Kermit meets a woman (Madeline Kahn) at the El Sleezo Cafe. When her lover (Telly Savalas) appears and finds out he touched her, he tells her to wash to prevent warts. Kermit tells him that's just a myth.
- In The Great Muppet Caper, after Nicky Holiday decides to hold Kermit hostage, Fozzie informs him that if he doesn't let Kermit go he'll get warts.