Anything that can be composted. If it can’t stand up to the ravages of the compost heap, you do not want to know what it’s deteriorating into in your stomach. Better stay on the safe side and give it a miss.
Bananas that slowly change from yellow to spotted to almost entirely brown and then back again, for obvious reasons (the reason is enchantment). Why are you even thinking about eating those bananas? Don’t click on that link and don’t peel that flickering fruit. Put it down. That’s not food for humans.
Anything from Taco Bell, not because Taco Bell is appreciably worse than most other fast food establishments, but for whatever reason it seems to have crossed the invisible line of demarcation most people drawn between “acceptable” and “unacceptable” fast food restaurants. These same people who drunkenly order “chicken fries” at Burger King once or twice a year will be sure to tell you every horror story they’ve ever heard about factory-bagged taco meat the second you mention you’ve been thinking about getting a Chalupa.
Cap’n Crunch, for that will tear up the roof of your mouth like you wouldn’t believe after only about half a bowl. Delicious, but not worth the pain. The sugar crystals feel like knives against your flayed palate. Stick with Honey Graham Oh’s. Safer.
Lobster. It’s just shrimp, but harder to eat.