tit for tat

Fred came from Cheapside in London – an official Cockney, born within earshot of the bells of St. Mary-le-Bow – and he taught her Cockney rhyming slang. She loved its lighthearted logic: the last word in a common phrase rhymed with the word it was to replace. So "tit for tat" was "hat", and "trouble and strife" was "wife". But the best part was that you usually dropped the rhyming words and used only the first words, so "your wife's hat" became "your trouble's titfer".]