Why does David Letterman bump the pole?

David Letterman bumps the pole as a humorous tradition on his late-night show, symbolizing his departure from the conventional norms of television. The act serves as a playful gesture that reflects his irreverent comedic style and willingness to break the fourth wall. It also highlights his unique brand of humor, engaging the audience in a lighthearted and unexpected way. Overall, it's a signature move that showcases Letterman's personality and approach to comedy.