I can do witty banter with the best of 'em. It has to be an extended conversation, though, since I like to incorporate things previously talked about with newer points in the conversation.
Or funny voices/impressions to make fun of someone or something. Valley Girl, Yoda, Movie Announcer Voice (thank you Pablo Francisco), etc.
Some of my favorite people to hang around with are those who observe something and then suggest this absurd change to it. Y'know, everyday comedy that COULD happen but didn't so they decide to imagine and ask 'what if' about it. Those are situationally funny, though, so I can't really give any examples without the standard 'you had to be there' problem.