i remember watching a tv show about STD's that had this live studio audience. one of the audience was a big Mike Tyson lookalike that was sitting in the front row looking very smug with himself, and laughing at the 'fools' who didn't use condoms for casual sex sessions with strangers.

it was funny to see his expression slowly morph from its smugness to one of abject horror, as one of the 'panel of experts' started explaining how destructive petroleum jelly (vaseline) is to condoms. appartently it only takes a matter of seconds before the jelly degrades the latex enough to cause holes large enough for diseases to get through, and only a few seconds more before the holes are large enough for sperm to get through.