People say you scratch my back and I'll scratch yours to describe the way that one person helps another because they know that person will help them in return. For men, commitments are based on common interest: I'll scratch your back if you'll scratch mine. Note: You can also talk about back-scratching, meaning help that one person gives to another so that they will be helped in return. There was a lot of mutual back-scratching between directors and executives. Note: This phrase is often used to show disapproval.