Funny inuedno, obvious rhymes that are substituted and not actually saying the rude words. The better limericks work that way....

One of my favourite naughty songs is by Jehosophat and Jones (The Two Ronnies) which has lines like:(this is an approximation, CRS has set in...)

Down in the hollow where the firefly flickers, see the girls swimming without no hesitation....

Has me in hysterics, but then most things do.....

Another is called 'we knew what she meant' which relies on inuendo. Lady goes into a department store and asks the attendant 'I need some material to make a new belt, perhaps you can tell me where I can get felt'.

Go for delicate rather than obvious and you'll find that most people will actually listen rather than just shout the rude bits out.

LTS