[It's hard to say what stops him first, the fact that she says "stop" or the fact that she addresses him the way she does. He pauses, lowering the can and dropping it with a huff as he rubs at the sore spot of impact. He winds up giving her a slightly sheepish look, though he's approaching the glass.]

I'm fine. I've taken harder hits than that...[Probably. Still. The can's set on the floor and he moves to the glass where he hit it with said-can.] Dunno what this is made out of that it's not even damaged. Ever seen anything like this before? [What about knocking on it with his knuckles? That probably won't hurt him but he can get an idea how thick the glass is, etc.]