“OK! Get off my back!”
Your wife is complaining because you spilled something and didn't clean up after yourself. She often yells at you for these kinds of things. You're annoyed, so this is your angry reply.
OK! Get off my back!
This is a very casual phrase that shows that you're annoyed when someone is criticizing you or telling you what to do. It means "Leave me alone" or "Stop telling me what to do."