American cheese, because I threw up once as a kid after I ate some. Honestly no big loss, I wouldn't eat American cheese now even if I'd never thrown it up because it's a trash cheese.
Also, any meat where I can tell what it once was. I don't want to eat anything off of a bone, or anything's skin, or god forbid a fish is served whole. Growing up we used to have whitefish sometimes on the weekend and no fucking thank you.