I'll try any food once. The only food I really dislike is onions, and even then, I'll try it - there are things they taste good in. I use onions in recipes frequently.
I also hate milk and white chocolate, but it's more cuz I hate how sugary my mouth feels afterward, not cuz I can't stand the taste.
The one thing I won't try is all those weird foods at the Florida State Fair. I'm good without fried butter or fried Pepsi or a cheeseburger served between two Krispy Kremes. That doesn't sound appetizing.