New York City hotels have free condoms in the rooms. All these years I've been using the free shower cap.

In this one-liner, Letterman uses misdirection and sexual innuendo to satirize the small “freebies” of hotel life and the way urban sophistication is marketed. The setup invokes a familiar detail—complimentary items in hotel rooms—then pivots to a deliberately absurd confession: mistaking a shower cap for a condom. The humor depends on the audience’s awareness of both objects and their very different purposes, turning a mundane amenity into a joke about ignorance, embarrassment, and the gap between intention and use. It also plays on New York City’s reputation for adult frankness and the late-night monologue tradition of pushing boundaries while staying in the realm of implication.