Mine's kind of a long story, and it has several parts, but here goes...
A buddy of mine from college actually looks like a pink monkey. He's one of those unfortunate red haired, pink skinned and orange freckled Irish guys--less compassionate people refer to these folks as Gingers. He has big monkey-like teeth, a big head, and he behaves pretty poorly. Not above flinging poop. We came up with calling him The Pink Monkey.
In college, I never did any real work until the night before the test or the paper was due, and I'd stay up all night, chain smoking and popping ephedrine (back when you could buy it at every gas station) like it was going out of style. I'd be up all night, and then go drinking once the test was over or the paper was in. I'd wind up drinking and smoking well into the night, with plenty of energy still going from the ephedrine, and I wouldn't eat much or anything all day. Combining a lot of booze with ephedrine, no food, and a lot of smoking, occasionally I'd wind up getting a light but stupidly terrible case of nicotine poisoning, turn a nice sickly green color, and become worthless for a half an hour, crumpled somewhere with cold sweats and no motor skills. I wish I had known about the sugar remedy that someone posted about today.
In addition to the turning green trick, I was also blessed with the magnificent ability to have a cold, germs, etc., but not to let it really bother me, and I'd just pass it along to everyone else I was around who wouldn't usually fare as well. Kind of like Typhoid Mary. Anyway, it's theorized that the AIDS virus came from the green monkey in Africa. Whether some dude was putting his weiner where it didn't belong, or some aggressive monkey bit him, I don't recall. I guess both could very easily have happened at the same time. So my role as a carrier of disease and general unhealth also contributed to the name.
Plus, I like monkeys.