An expression used commonly to refer to a seemingly impending fight or confrontation that will usually result in someone or multiple persons getting the shit beat out of them. Often heard when one person insults another's mother or girlfriend and the man insulted enough is ready to flip.
To be up "Shit's Creek" is to be in serious or complex trouble, such as to (literally) be "up a creek without a paddle." It is synonymous with Urban Dictionary's expression "Shit Street" and is possibly its antecedent.
"When the deal fell through, we were up Shit's Creek".
"If he gets caught again he will be up Shit's Creek."
Phrase used to simply describe something mind-blowing or deeply philosophical in nature. Often said when too lazy to reply in an equally sophisticated or intellectual manner.