A man goes to his doctors to pick up his wife's test results.
DOC: I'm affraid there's bad news.
MAN: What is it?
DOC: Well, we're not sure. Your wife has either Alzheimers or AIDS.
MAN: Bloody hell! Well, which one is it?
DOC: Dunno. But there is a test you can do.
MAN: Which is...?
DOC: Put her in your car and drive her out into the middle of nowhere.
MAN:Then...?
DOC: Leave her there. If she find's her way home, don't fuck her.