It depends. If they look like they’re doing it on purpose as a game, frown and move on. If it looks like something is really wrong, I’d ask him to see if he responds. If he says he’s okay, I’d move on. Otherwise I’d yell out to all the other people on the street in a vague panicked scream in case one of them is a trained professional. Then I’d dial 911 on my cell phone. If I wouldn’t have one, I’d frantically run around looking for someone else to ask to call.
