Rinktum was still in use when I was a boy in the 1950's to mean rubbing the knuckle on a fresh haircut. My grandfather also sang "Froggy Went a'Courtin'" with the "laddie come a rinktum ki-me-o" chorus which he claimed was from the Cherokee. Part of the chorus also included the words "Captain Karo", but I've forgotten the rest - have it written down somewhere.