Marty McFly: Okay, everybody let's back up now, huh? Let's back up... let's everybody back up, give him a little bit of room, okay? A little bit of air. It's okay, I know CPR.
[to CPR Kid]
Marty McFly: I know CPR.
CPR Kid: What's CPR?
Biff Tannen: [coming to consciousness] YOU!
[Marty knocks out Biff]
Marty McFly: It's fine.
CPR Kid: Hey? Did you just take his wallet?
[to the crowd]
CPR Kid: He just took that guy's wallet!