Scratch Someone's back(return a favor)
Hey, Bea. I need some help stacking these boxes. Would you please give me a favor?
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.
tidy up = •Ð‚¯‚é