It’s an adjective and it means having or showing a bad temper; being annoyed and irritable; being cranky or disagreeable. You know the sort of person, they come into work pissed off with everything and everybody and just looking for an excuse to blame somebody for everything that is wrong in their crappy lives, the world, the universe. Thoroughly unpleasant shitbags.
When you have to pee in a movie but don’t want to miss anything, and must do the following mental equation: will the amount I have to pee cause enough discomfort to diminish my attention capacity for the remainder of the movie to an extent which is greater than the amount of the movie I would miss by making a mad dash to the restroom.
I saw Satantango last night, wonderful film but by the 5th hour I had to start doing pee calculus.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).