I came upon this topic last week on smitten kitchen and it's urked me ever since. It was regarding dunking cookies/biscotti into a liquid.

I've come to notice that alot of people, like myself cannot deal with the crumbs that are left behind in the milk/coffe and find it just plain gross.

My food OCD is

dunking cookies into milk. Can't deal with a soggy cookie and crumbs.
digestice cookies in tea. They disintegrate, it's just plain gross.
a plate that is served on one side hot pasta and the other salad. Can't deal with the 2 temperatures. Salad must come in a seperate dish!

Lets hear about your food OCD, cause I know I'm not the only one out there.