The doctor tells him, "Sit down, I have a couple of pieces of bad news.

Firstly, you are showing the early stages of Alzheimer's Disease, but I'm very sorry to tell you this, you are also HIV positive, and are days away from developing full-blown AIDS."

"My God!", says the guy, and pops off to meet his friend at the pub as arranged.

"How'd it go?" asks his friend.

"Not so good. The doctor tells me I'm starting to show the first signs of Alzheimer's...

and... oh, shit... there was something else..."