He's commenting on how Stokesie is eyeing these girls while being married with kids, making a statement about his morality.

He's very excited at this sight, he likely doesn't get a lot of feminine attention/see a lot of girls (potentially a loser-type situation), VERY clearly objectifies these girls and reduces them to their appearance, and generally gives off creep vibes. He's been staring at these girls down to detail for what would realistically be a long time, it's concerning.

The speaker is reflecting common sexist sentiments that men hold toward women, ironically asking if there's anything in girls' heads or just an echoed buzz, calling them ditzy and dumb.

Stokesie seems to be more of the lighthearted, morally grey character in this story, from the way he joked around with the speaker earlier, checked out the girls, and through his characterization here, where he is shown to be nosy enough to alter the way he does his job in order to hear the ordeal going down.

The speaker notes what he believes are class differences between him and the girls in the store based on the snacks they came in to get, believing their parents drink expensive alcoholic drinks frequently while his see a beer as more of a luxury.