Get Off Someone's Back = stop bothering someone
从某人的背上下来,表示停止麻烦某人.
范例对话
A: Hey, John. I'm bored. Come on, let's go out and do something.
B: Sorry, I'm right in the middle of studying for a physics exam. I won't be able to make it tonight.
A: You've been studying for a long time. Why don't you take a break? Come on! Let's go! Forget studying for a while!
B: Look! Get off my back!I can't go anywhere!
A: OK. I'll stop bothering you only if you promise to let me know the minute you're finished.