@Chameloshi: It does make sense for it to be spaghetti, because he's saying he puked on himself, "There's vomit on his sweater already, mom's spaghetti", I think the line is to convey a scared nerdy kid.

@zenitix: Well, judging from the context of the entire intro instead of just that one line, he most likely vomited due to stress and being nervous about how he'll perform, and his mom, for some reason, is trying to forget about it.