When someone is full of piss
, they are in a very bad, bile
For example, whenever I'm stomping about the house in a generally angsty teenage mood, my mom will warn my sister, "Watch out! The girl is full of piss and vinegar today!"
I've heard that 'full of gar' can be used as an abbreviation as well, but I think it's much more fun to just say piss and vinegar.