Piss

Etymology
Piss is thought to be onomatopeic in that its pronounciation sounds like the act of peeing, which explains why it appears in multiple languages. From there it gets complicated. No one is sure exactly where 'pissed off' comes from although it seems to have originated around WWII. The British think 'pissed' means drunk while the Americans think it means angry.

Essential use in cinema: Desperado
Although Desperado contains the infamous piss joke as told by none other than Quentin Tarantino (too long to reproduce here) it also features a surprising number of other lame references to piss - normally in reference to the quality or temperature of the beer, e.g. -

Cheech: What do you want?
Buscemi: Beer.
Cheech: All I got is piss-warm Chango.
Buscemi: That's my brand.