The girls in their bathing suits flaunt their wealth, as they've obviously been lounging by the pool or beach while the people in the store have been working. As Queenie speaks, Sammy envisions the type of background she might come from, coming into A&P to buy fancy herring snacks for her parents.
Sammy's defense of the girls also involves a hope of impressing them, but they shuffle out of the store without taking any notice of his sacrifice on their behalf. He is from a lower class and is beneath them, which adds another element to the foreboding feeling he has about his future. Looking back at Lengel's weariness, he realizes that he, like Lengel, is stuck in the working class. While the girls' class protects them from the consequences of their actions—Queenie draws from a reserve of superiority when she remembers her place in the confrontation with Lengel—Sammy has to face the consequences of his actions without any protection of wealth or class.
Class Quotes in A&P
"My mother asked me to pick up a jar of herring snacks." […]All of a sudden I slid right down her voice into her living room. Her father and the other men were standing around in ice-cream coats and bow ties and the women were in sandals picking up herring snacks on toothpicks off a big plate and they were all holding drinks the color of water with olives and sprigs of mint in them. When my parents have somebody over they get lemonade and if it's a real racy affair Schlitz in tall glasses with "They'll Do It Every Time" cartoons stenciled on.
"We are decent," Queenie says suddenly, her lower lip pushing, getting sore now that she remembers her place, a place from which the crowd that runs the A & P must look pretty crummy. Fancy Herring Snacks flashed in her very blue eyes.
The girls, and who'd blame them, are in a hurry to get out, so I say "I quit" to Lengel quick enough for them to hear, hoping they'll stop and watch me, their unsuspected hero. They keep right on going, into the electric eye […]
I could see Lengel in my place in the slot, checking the sheep through. His face was dark gray and his back stiff, as if he'd just had an injection of iron, and my stomach kind of fell as I felt how hard the world was going to be to me hereafter.