What's the best way to mess with the tightly wound?

Ignore them as they unwind

“Is there meant to be flames inside your oven?”

@rebbel yes :D

Listen to them and play Devils Advocate.

“You were such an ugly baby, your mother fed you with a catapult”

Laughter

I once worked with a guy that was wound tight. Not only was he borderline OCD, he was paranoid as well. Very difficult guy to get along with. One day, during lunch, I was reading a newspaper. I got an idea. I cut out an article and stuck it in his mail slot. Others in the room asked what I did and what was on the article. I told them I didn’t really care what was on the article. A little while later, the wound guy came in, saw the article in the newspaper in his slot, pulled it out and asked “What is this? Who put this in here? What does this mean?” Everyone played dumb. The next day I put another article in his slot. And the day after. One day it was the 5 day weather forecast with Wednesday highlighted. It was driving him nuts. He was trying to figure out who was doing it and he pretty much narrowed it down to me until I was off for a few day vacation and the articles kept showing up. Turns out everyone thought it was so much fun they had filled a file in the file cabinet with random clippings and one would be put in his mail slot every day. Lots of fun for about 2 weeks until the boss finally told us we had to leave him alone.