TIT FOR TAT

{n. phr.} Equal treatment in return; a fair exchange. * /Billy hit me, so I gave him tit for tat./ * /I told him if he did me any harm I would return tit for tat./ * /They had a warm debate and the two boys gave each other tit for tat./ Compare: GET BACK AT, EYE FOR AN EYE AND A TOOTH FOR A TOOTH.