get off someone's back

Image acquired from Wikimedia Commons and used with permission. Image attribution: public domain via Cmd.808.

Explanation:

Imagine that you are looking for work, and you see an advertisement for a high-paying job in a newspaper. The job description says that a large company needs someone to provide transportation for their new CEO (the chief executive officer, the manager for the whole company). You apply for the job and get it. However, when you arrive for your first day of work, you find out that the kind of transportation you will use is not a car, a motorcycle, or even a bicycle; the transportation is you! You have to transport the CEO on your back (called a piggyback ride in English) everywhere he wants to go. This includes taking him to the restroom!

One day, after he has finished using the restroom, you start to carry him back to his office, and you smell something funny. You look down and notice that he didn't wash his hands! You tell him to immediately get off your back, and you quit the job the same day! Now, we both know that, while at work, you don't have to actually carry your supervisor on your back (I hope), but you may have a supervisor who comes into your workspace all day long to look at you, and make sure that you are doing your work. This can give you a feeling similar to the one you would get from carrying your supervisor on your back.

Variation: Some Americans also use the expression "get off my case" which means the same thing.

Note: This expression is considered impolite (not polite) in English. If you tell someone to get off your / his / her back, you should expect to get a negative response from that person.

When someone is constantly watching and bothering me, I can tell that person to get off my back.

Example:

Sally: Martin I'm home from work.

Martin: Yeah. Great.

Sally: Hey! What's going on here?! I just came home, and again, you're sitting there watching cartoons! You told me you would look for a job today.

Martin: Yeah. Yeah. I'll do it tomorrow.

Sally: That's what you said yesterday. I mean, look at you Martin. Look at what you've become. You're 38 years old now, and you're sitting there watching kid's cartoons. You have a jelly stain on your shirt that's been there for three days, and you smell like you haven't taken a shower in two weeks!

Martin: Could you please keep your voice down? I can't hear the TV.

Sally: That's it Martin! I can't take this anymore! Either you look for a job right now, or you pack your things, and get out of this house!

Martin: O.K. mom. O.K. I'll go and look for a job. Get off my back!

Sally: And that's another thing, Martin; I want you to stop calling me mom. For goodness sake, I'm your wife!

Martin: Whatever you say lady.

If you would like to learn to speak English clearly (like Martin and Sally), you should check out the Speak English like an American course (aff).