Greg was a little "ewww" at the idea of cutting open his bear's brain, even if he doesn't really like the stupid thing, but once he saw the little beanbag he couldn't help but smile. No wonder Muggles are dumb if their brains look like that!
Again, he found it was pretty easy to cast this spell. The brain turned the right colour and consistence, although the smell of sulfur was a little bit stronger than on others' bears.