The Perfect Pizza

Whenever I think of the ontological argument (and I do that as little as I can, but Anselm keeps popping up these days), I think of an example I used primarily back when I taught at Radford.
No disrespect intended: we can compare Anselm's thoughts about God to the perfect pizza. The crust is just right, neither too thick nor too thin, not too chewy or crisp, not over- or under-cooked... ditto with the sauce, the cheese, and whatever other toppings you might desire. After all, it's the perfect pizza. Here's where we get back to Anselm: what would make that pizza you're currently thinking of even better? Well, it would be even better if it were here right now, i.e., if it existed. Since Anselm was talking about God and not a pizza, he could say that, since God is "a being than which nothing greater can be conceived," then God must exist. (Just as the truly perfect pizza must exist--but there's nothing inherent in the concept of a "pizza" which makes it necessarily perfect in the way that God is.)
The thing I particularly like about this example is that it addresses the problem of our finite imagination. We don't know what God's perfection consists in, but we can see that our differing ideas of what makes a perfect pizza can point towards some ideal. Whatever our notion of perfection is, God must be greater than that, but because God is that being than which nothing greater can be conceived, however else we imagine God, existence is a necessary perfection (i.e., a God that didn't exist wouldn't be perfect).
Now, if that argument doesn't make sense to you, please don't blame me: blame Anselm. That is, something has gone wrong here, but it's difficult to say exactly what. It wasn't until Kant came along in the eighteenth century that we see where the problem lies.