“What do you call it when 20 ox run into each other?  A yakksident.

What do you call it when 20 yaks run into each other? An occident.”

This joke is an example of a meta joke — it was given as an example as a bad joke, and, according to the informant, was in fact passed around as a common reply when someone told a bad joke.  According to the informant, it is also used to salvage a bad joke, by telling a worse one that makes the first joke told better in retrospect.  The joke teller is aware of the joke’s awfulness, making a punchline out of the poor, slightly nonsensical punchline.