Ugh... Why not?

The other day I went up to get Cameron out of his crib after nap and this is what I found. He has figured out how to take off his crib sheets and refuses to keep them on. I have put them back on numerous times and every time I go in to get them they are off. So I say, Why not? Let him sleep on uncomfortable vinyl matress cover if he wants. Its one of those pick your battles type things and this is one not worth picking.