Tomatoes are the only food I've encountered that trigger a gag reflex in me. Tomatoes make me physically wretch. It's so strong a sensation that I can detect a single tomato seed in a sandwich that has been de-tomatoed.
Sometimes people find it strange that I have no problem with pasta sauces, ketchup, or even tomato soup (it goes great with grilled cheese sandwiches). I say that they taste nothing like an actual tomato.
Does that make sense? Am I insane?