I’ve always liked this joke:
Man #1: You look familiar. Did we meet at a convention in Chicago last
Man #2: No, I’ve never been to Chicago.
Man #1: Neither have I. It must have been two other guys.
I think it might be because it doesn’t follow the standard joke-pattern. It’s not just the last line that is absurd on its own. It makes you jump to a higher-level and think about how absurd the entire conversation is; that nobody would actually have said the first line.