Anything I ever ate in Butlins' staff canteen (which was just the other side of the Res Cat kitchen so it was the same food that the full- and half-board "guests" got). Cold beans, soggy toast, cold, powdered, scrambled egg, cold, burnt sausages, cold, over salty bacon, and that's just for brekkie. Don't even get me started on lunch. Let's just say; you only had one choice of meat for your Sunday roast and the pasta bake was always chicken on a Monday!?!
Same goes for the canteen at college now, though only as far as breakfast is concerned, we do a good fresh spread for lunch every day, thank goodness.