Dogs, dogs, dogs. Do you know where that frisbee has been? It's disgusting, absolutely disgusting that you'd even consider putting your mouth around it. Plus, it's such an awkward shape, it can't be easy to hold onto.
Everyone else ever in the whole world catches frisbees with their hands, but you have to do it with your mouth. I don't care that you don't have any thumbs! That's no excuse, goddamnit!
And yes, I do realize that there were at least five good "that's what she said" jokes in there that I passed up. I'm mature, dogs, unlike you.
(flickr photo the superdog by jared; http://www.flickr.com/photos/generated/3248455087/)