Pre-game dunking by the V team during JV warmups

[ChuckElias]

You can't penalize a team for the actions of a person who is not on that team, except in very specific situations. (And even then, we're told only to penalize when absolutely necessary). In this situation, the kid who dunks isn't on the team. That makes him a follower of the team, nothing more. Would you T a kid in street-clothes who came on the court and dunked? No, you'd tell him to get off the court. Same here. No penalty. Get him off the court.