Stomach thing?

Ok this is gonna sound like a weird question but w.e. Please be nice. Ok so im kinda skinny and w.e but when i eat something my stomach gets really big, and i think its called bloating rit? Well Why? I mean like all i have to do is eat like a little breakfast bar and then my stomach gets all big? None of my friends stomach gets that big? Its embarrasing after lunch if i have on a shirt. I kow this is kind of a weird queston but please answer. Some of my friends are a little chubier than i am, does that have anything to do with it? Not that im against chubby ppl i swear, im just wondering whats up with me.