Imagine a barber who gives free haircuts to all the people in the village. One day, a man comes along and asks the barber if he cuts his hair too. The barber replies, "Of course, I do. After all, I am a barber." But here's the catch: If the barber cuts the man's hair, he must also cut the hair of all the other people in the village who don't cut their own hair, because they come to him for a haircut. But if he doesn't cut the man's hair, then the man must be one of those people who don't cut his own hair, in which case, the barber is obligated to cut his hair! This creates an infinite regress of paradoxical logic, where the barber is simultaneously cutting and not cutting his own hair.
The Liar's Paradox: A Tale of Self-Referential SillinessOr, if you're feeling particularly nihilistic, you can try:
The Grand Hotel: A Paradox of Infinite Rooms