Sam could tell that he had somehow managed to annoy the boy. The change in his stance, the sharp tone of his voice, the mere look on his face. Adding that to the weird clothing that he was wearing and Sam would have easily been able to decide right then and there that he was outright out of his mind. The talking to himself, the wild, angry response to his approach, and the clothes that he was wearing? Yeah, it wasn't looking so good. Sam would have stopped to wonder if he had escaped from an institution somewhere if not for the fact that he was still feeling quite fascinated by the device in the boy's grip.
"No," Sam answered right away, "no, I wasn't. I was actually going to come and ask you what that is." He nodded to the device. "If you don't mind, that is. I've never seen anything like it before. Or..." Sam looked at his clothes, frowning. "Are you some kind of security guard or something?" Yeah, right. More like a LARPER. Or a janitor with a little too much time on his hands.
Possibly also crazy. Sam was still not straying from that thought right away.