Idiom of the day :- Scratch Someone’s Back

Usage, examples and definition of the Idiom :-

Hey, Bea. I need some help stacking these boxes. Would you please give me a hand? OK. And I need some help tidying up the house. How about your helping me out after that ? OK. If you scratch my back, I’ll scratch yours. I know you don’t like doing housework, but I’ll help you with the boxes if you promise to return the favor. No problem. I’ll even do the windows.