Mushrooms are totally disgusting (mostly a texture thing)
Brussel sprouts, broccoli, or any green vegetable with 'that' taste - especially cooked. Yuck!
I had this fish paste on some bread in Sweden once called, Kalles Kaviar. I mean, it was the absolute worst thing in the world - I still cringe thinking about it...and I generally like seafood - although I have no idea how people eat raw oysters and not gag.
Oh yeah, tp for an original topic!