Another Explanation
I've been working on this wiki for a while now without attracting any volunteers to speak of. Maybe I am the only person in the world that finds this idea interesting, but I find it so fascinating that I thought I'd take another crack at explaining it.
One thing it's a bit like is Family Feud. You think of some category--astronauts, waterfalls, gamblers, whatever. What's the studio audience going to name as being in that category? When you've got all the things that you'd expect someone else to list, the category's done.
Another thing I'd compare it to is Father Guido Sarducci's Five-Minute University, an old Saturday Night Live routine. The joke is that you can learn in five minutes everything you'll remember five years after you graduate f…