bum-tit-tit
In 30 years I've never known anyone other than those who went to St. Michaels Primary School who sang this. Prove me wrong: "Bum Tit Tit! Bum Tit Tit! Turn the hairy handle now" "Bum Tit Tit! Bum Tit Tit! Hear the willy orchestra"
written by Ad*m *uc*er, approved by Log
There is also a form which includes "play the fanny banjo now"
written by He*ene*Magi*ness, approved by Log