OK.. I'm not a Vet or an animal psychologist, but here goes. I have one cat who would, I swear, climb mount Everest to get hold of a (real) rubber band and chew it up and eat it. She also eats thread... yep that's a pain, and a few other types of plastic bits, so we have to be VERY careful of them as some can be quite harmful.. I don't think it's the suckling thing because of the difference in nipple sizes.. (honestly, ever look at a cat's nipple?) I think it's the material.. our other cat can ferret out one of those "wrapped" elastics for ponytails from across the room.. he doesn't eat them, just plays with them and steals them.I don't know what you do about it.. but be careful if you use some food substance on them as garlic, onion and that sort of thing are not good for cats, and can be fatal.