Scrump (12th Feb). I think you're thinking of the routine the late Bob Monkhouse did (repeated occasionally since in clip shows) in the early sixties. He was attired in Beatles suit and wig and was being 'interviewed' by a voice off camera. He answered the questions by miming to little clips from pop hits. And one of the questions was indeed 'is it true that you never wash?' and the answer was as you described (taken, I think from the Peter Paul and Mary version of the song).