To get Dire Aids you must get in a fight with a dire animal (Snake or Wolf) while in Canada. While fighting let the dire animal bite you without blocking and it should say you have Dire Aids. The only way to get rid of Dire Aids is to go to the doctor while in Canada. So don't do that.
You can also get the "Face Hoff" & "Two Girls, One Stick" achievements by buying The Hasselhoff for $175 at Tom's Rhinoplasty and wearing the entire makeover disguise (makeover wig, makeover outfit, makeover accessory, & makeover makeup)