A man noticed his wife wasn't quite the same as she used to be. So he takes her to the doctor. The doctor does a bunch of tests and says he will get back to him in two weeks. Two weeks later, he calls the man and asks him to come into his office.
"Thanks for coming" he says, " I'm afraid I have some bad news. We have two patients with the same name and there seems to have been a mix-up with their records and test results. All I can say for sure is that one of them has Aids and the other has Alzheimers."
The man says, " What am I going to do? How do I know which one my wife has?" "Well," says the doctor, "I could order some more tests, but that will take a while, so in the meantime, I suggest this: on your way home stop off at the supermarket and "accidentally" leave her there. If she makes it home, don't sleep with her any more!!"