Regarding the kid 'blowing up', that was more of an ironic death than a humorous one.
He just said 'The cop pulled me out of the way of the news van and saved my life', then he gets up and goes to the grill and BOOM! I found humor in it because of how sudden and overdone it was.
You see a long shot and just outta nowhere KABOOM the kid blows to bits. It was just so unexpected and huge that it was hilarious.
Like the scene in Bride of Chucky when the dude steps out onto the highway and explodes as the truck hits him (actually before the truck hits him, but thats a different story). It just came outta nowhere and was so big and unexpected and gory, that it just induces laughter. I wasnt the only one at the theater that burst out laughing when it happened. It really caught everyone off guard, and thats why we all laughed.