I'd probably just continue to stare at him until PU signaled "play".
Then on with the game. Normally a glare will either a) get him to shut up because he feels a threat to his existence in the park or b) get him to be 1) personal 2) profane 3) prolonged
Either way we get a solution to the problem
Edited a couple minutes after my post (after thinking about it some more):
I would look away at first and not have rabbit ears. If I felt he was getting more than just an initial reaction or opinion in there, and really yelling at ME, then I'd probably start my glare.
Edited a couple minutes after as well because I spelled "Edited" "Editted"