To overkill a joke. When a joke is told by one person and then someone else keeps piggybacking and adding on to that joke until, at last, it has no humor left in it.
Man, we were having a couple of beers the other night and this chick walked in with those UGG boots. We all started laughing at her, but Jimmy kep going and going and going. I felt kinda bad, but he should've known he gained it.