unicorns
Explanation
The Joke
A grandmother tells a child that unicorns live in the woods and will only play with you if you are a virgin. The child asks how the unicorns would figure that out. The grandmother says: "They just know." A unicorn then appears from behind a tree and declares: "I can detect an intact hymen at 200 paces." The child says: "I think I am done with unicorns." The grandmother agrees: "Yeah, they creep me out too."
The Humor
The comic takes the classic medieval legend that unicorns can only be approached by virgins and makes the implicit creepiness of the myth explicit. The traditional telling presents this as a magical and pure connection between innocence and a mythical creature, but when the unicorn itself explains the mechanism -- it can physically detect hymens from a distance -- the whimsy is instantly destroyed and replaced with something deeply uncomfortable. The joke highlights how many fairy tales and myths contain bizarre or unsettling premises that we accept without question until someone spells out the literal implications. The grandmother and child bonding over being mutually creeped out provides the punchline, as even the characters within the story recognize how disturbing this is once stated plainly.
References
The association between unicorns and virginity dates back to medieval European lore, particularly popularized in the famous "Hunt of the Unicorn" tapestries (circa 1500). In these legends, a unicorn could only be tamed by a virgin maiden, which was often interpreted as a Christian allegory for the Incarnation of Christ through the Virgin Mary.