My current horse is actually quite picky, but he asbolutely loves cereal bars - especially raisin bars (cant remember who makes them, Special K or something).
My last horse would eat anything - he especially loved drinking juice (fruit juice or sprite etc.) from my bottle...
Well, i dont think my 16.2 warmblood knows what he's eaten 'cause he doesnt bother to smell it, its straight down and gone before you can take it off him - This has resulted in a packet of polos IN the packet, a packet of fizzy straws, again SEALED packet left on the side, bottles AND cants of pop he has got his teeth rounf - he can even take the lid off bottles and a bacon and egg butty that i put on the side to leg my friend on her horse. NOT happy at having to queue for another!!
Puppy, I do get the impression that most of these "weird foods" were not fed deliberately. I don't tend to feed my pony weird treats (excepting prawn crackers, which he really appreciates), but he's made attempts on everything from cheeseburgers and ham sandwiches to coke bottles and a fifth-place rosette. This usually earns him a telling-off, but doesn't stop him from trying again the next time he fancies a snack!
No, really why would i feed my horse things in the wrapper?? These are thigs that he has stretched his 'giraffe neck' over to pinch! haha. Anyways, he did try birthday cake icing yesterday - no complaints on that either