corpse

That's what the textbooks say, anyway. . . . although I have no idea why! It's easy to remember though, so I'll roll with it. (it seems like most of the kanji involving butts, farts, or pee have this, so maybe that is the origin?)

Anyway, think of it as a dude that died and his upper body toppled over, while his legs are standing up due to rigor-mortis.