Look what you did you little jerk

I would doubt Uncle Frank doesn't care who spilled Pepsi on him, as you can see the he hates Kevin since he was the one that started it by running into Buzz, and I don't think common sense makes sense to him in the first place either.

Uh, it's been a while since I watched it but I'm pretty sure the soda and milk was spilled because Buzz was knocked into the containers of them after Kevin pushed them. So it was his fault. And yeah. Since he's the youngest they don't let him explain why he fought with Buzz. But still, fighting is wrong and I can't really blame them for being angry with him about it. Frankly though I'd kind of like to kick Buzz in the groin for acting the way he did in that scene.