Well... you can feed them anything that isn't a cookie. Or even a single cookie would be fine, just so long as it doesn't pluralize into cookies. He won't be upset unless you feed cookies to the crocodiles. I might even be a bit upset if you feed cookies to the crocodiles :S
I would ban you for suggesting banning the Muffin Man... but I find myself unable to ban such a lovable fellow
I would ban you for suggesting banning the Muffin Man... but I find myself unable to ban such a lovable fellow

Please give me a home where cloud buffalo roam
Where the dear and the strangers can play
Where sometimes is heard a discouraging word
But the skies are not stormy all day