get away with (someone or something)
1. To avoid the consequences of one's action. You'll never get away with cheating—one of your teachers is bound to figure it out. You got lucky when you ran that red light. Next time you might not get away with it.
2. To leave or flee with someone or something. The robbers got away with the TV but not much else.
get away with you
An exclamation of surprise, disbelief, and/or incredulity. Oh, get away with you—you know that's a ridiculous claim to make!