When a lady jiggles her ass region in such a way as to cause the ass cheeks to collide, or "clap". Often seen in pornographies that focuses on a lady with a large "bo-donk-a-donk".

I have no fuckin' idea, but it was in Achewood so I figured 400 people would have come by here already to make up a definition. Maybe today's comic had too many words and not enough pictures of cats looking shocked, so fewer people read it.