(Context: the following joke is kicking around the NY State health
department right now, because some NY media types have finally
broken down and started mentioning condoms and AIDS in the same
breath, but are not discussing how one would use a condom in actually
preventing AIDS.)

Two junkies are sitting by the side of the road, happily shooting up
whatever it is that happy junkies shoot up with, and generally
having a good time. A socially conscious individual walks up and notices
that they are sharing a needle. He lectures them about AIDS and the
danger that comes from sharing dirty needles. One of the junkies looks
up and says, Its ok, were wearing condoms.

— Richard Welty