return the compliment

Also, return the favor. Repay someone in kind, as in Her political opponent came out with a smear campaign, and she returned the compliment. Neither the compliment nor the favor in this idiom is necessarily desirable. [First half of 1700s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.