In undergrad my wife used to take a tape recorder to class and then write notes from the recording later. This "game" (more specifically the variation that boxley describes) was described in a physiology class, along with a complete explanation of exactly how dangerous it was.

And yes, I've heard of the use of choking in sex as well. I heard about that from a brother who mentioned that on average 1-2 marines die a year by trying to asphixiate themselves while masturbating.

Cheers,
Ben