scratch someone's back
原文解釋: to do a favor for someone in return for a favor done for you
中文解釋: 人與人之間的互助關係,相互幫助。
已下為例句:
1. You scratch my back, and I'll scratch yours.
2. We believe that the mayor has been scratching the treasurer's back.
3. I do have some information you might be interested in,