In the short story "A & P" Sammy is just an average teenage boy working at a supermarket. He seems to be kind of shy and probably does not voice his opinion much in situations. When the three teenage girls enter the supermarket in just their bathing suits, rather than scolding them for being indecent in public, he simply observes them as any teenage boy would do. He was obviously attracted to them, which you can see when he comments on how they look and their actions.
When the three girls approach him at the register, he is stunned by the girl with her straps down who pulls a bill out of her top. The girl probably senses his attraction and is purposely trying to attract his attention further. When the manager opposes to the girls for being indecent in the supermarket, they argue that they are decent. Sammy felt that his manager Lengel was being a little too hard on the girls, he also felt that his manager was trying to humiliate him in front of the girls.
As the girls are walking out of the store, Sammy attempts to catch their attention by yelling out "I quit!" His manager is shocked by his sudden defiance and threatens that he is going to disappoint his parents by quitting. Sammy does not care that he may disappoint his parents, he is influenced by the girls defiance to authority and persists in quitting. As Sammy is taking off his apron and heading out the door, he realizes that the girls have already left the store. He still does not regret quitting and continues out the door to go find the girls.
Overall I think this story showed how strongly girls can influence teenage guys, especially girls who are only halfway dressed. When Sammy saw one of the girls talk back to his manager, he thought he would impress the girls by having the same attitude. Sammy is probably not a very bold and out-spoken person, but this situation gave him the opportunity to stand up and give his opinion.