My father grew up in the Fort Worth, TX, area, born 1928, and went to UT 1945-1950. He taught us to say "no rinctums" specifically to everyone you saw after getting a haircut. If one told you "rinctums" first, they got to rub their knuckles up the back of your head--the harder, the better. This led to, and still leads to, lots of conflict after haircuts, together with creative rules on when "no rinctums" works or doesn't work.