In military parlance it means anything crappy coming from the top of the chain of command will hit everyone down to the bottom. This includes dumbass decision making, disciplinary actions, or simply a superior taking his frustrations out on subordinates.
Privates, I'm knee deep in your assright now because the 1st Sgt was knee-deep in my ass this morning, and shit rolls down hill!
Something you say questioningly when you misheard a friend. Derived from a conversation between two friends, in which one misheard the word "staples" and thought she said "Snape Rolls."