Sam shrugs a little, because, no, he’s not an expert on fireworks - or on anything, not yet ‘cause he’s still young, and you don’t get to be an expert on things until you’re older, once you’ve learned more; someday he’ll be an expert on something, but it probably won’t be fireworks, even though they are pretty awesome - but he doesn’t say anything. Besides, Dean’s getting his gloves, too, so that means Sam’s won at least half the battle. He grins, but he doesn’t say anything about that, either (drawing attention to his victories tends to annoy his brother, and now is not the time for being annoying). Now if Dean wants a sparkler, he won’t have to worry about burning his hands off.
He picks up the jacket off the couch and pulls it on, and then moves off towards the door, trying his best not to bounce with excitement. Dean doesn’t usually get mad about him fidgeting (not like Dad does, anyway), unless he’s already in a bad mood or they’re sharing a bed and Sam’s kicking him or something - but he doesn’t want to risk it, anyway. Or, more importantly, he doesn’t want to look like an overexcited kid. Dean needs to think he’s being really really good, so they can do things like this more often.
He shuffles a little in place, though, because he can’t completely be still. “Ready to go now?”