Everybody does something that they just can't stop doing- or at least knows someone who has a habit like this. Or, we all know someone who has weird rules for themselves, like someone who will only take showers but not baths.
I, for instance, cannot stop cracking my thumbs. I crack them all the time, and have ever since I had surgery on one of them. I don't crack my index finger or anything other than my thumbs.
Also, I don't mind drinking after someone, but I absolutely cannot do it if it's milk. I have no idea where this came from, but milk is in a separate category for me.
I will also not watch any animal being harmed on television, no matter if it's real or not. I'll watch those National Geographic specials all day but once they show the slowest zebra getting attacked, I'm out. I understand it happens in real life, but my theory is we all use the bathroom in real life, too, and no one wants to see that on television either. If I wanted reality, I wouldn't be watching television, I'd just go look out the window.
One of my best friends has a rule where he cannot sleep with a girl if he knows anyone else that has had relations with her. He also applies this rule to famous people, so if he knows, for example, that Matthew Broderick has had sex with Sarah Jessica Parker, then he doesn't find her attractive at all because of this. It is the most annoying and strange thing I have ever seen.
Me: Would you do Eva Longoria?
Him: Nope. That dude from 'N Sync was with her. That's gross.
He'll apply it to his personal life, too. The girl doesn't have to be the big 'v," he just cannot be familiar with the guy who was with the girl. If he sees the dude, she's crossed off his list.
This may tank as a thread idea, but I thought I'd throw some of these out there to see if anyone else some strange stuff to pass along.