scratch someone's back

1. Do someone a favor in hopes that a favor will be returned. For example, I don't mind driving this time—she's scratched my back plenty of times. It also is put as you scratch my back and I'll scratch yours, as in If you do the laundry I'll do the cooking—you scratch my back and I'll scratch yours. This idiom was first recorded in 1704.

Example Sentences

Add to it a robot’s ability to perform a task—like dispense medicine, scratch someone’s back or sweep the floor, and a Jetson’s like future doesn’t seem that far off.

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