Literally anything with gluten in it. Celiac disease is no fun, let me tell you. Nothing with wheat, barley, or rye, and I even have to be careful about quinoa (some cultivars have a protein in them that mimics gluten and causes the same reaction). I've had to stop eating a lot of my favorite foods, and I've become a label hawk. Says something about going organic, though!
I desperately miss my grandmother's fried chicken, though. I can make fried chicken myself with gluten free bread crumbs, but it's just not the same.