It's a bit more problematic when I'm holding him and he does this wild gyration of joy. This morning, when he brought his head forward after flinging it back, he brought his skull directly against my lower lip. He looked duly dubious after the impact, but only dubious. I think I have a fat lip. When he looked up at me after he had absorbed the impact and I smiled at him, he gave me a big grin back and wiggled contentedly. He usually does the head banging against my chest or shoulder, and occassionally my chin, but it's a bit easier on both of us when he does that. I'm going to have to figure out how to hold him so he doesn't whack my mouth again.
Still, it's hard to be grumpy when he's just so happy to see me.