turnabout is fair play

saying2

1. •
   It is allowable to retaliate against an enemy's dirty tricks by using the same ones against them.

   • No, I won't, — I went to my bed last, — let my bed come to me now, turn about is fair play. — 1795
2. •
   Taking turns is morally right.

   • Turnabout is fair play, right? We'll start it low and take turns, I'll tase you, and then you can tase me, and we'll see who the last man standing is. — 2015