How we cite our quotes:
Policy is what the kingpins want. What the others want is juvenile delinquency. (18)
A kingpin is the person in an organization with the most power. In the A&P that's Lengel. Sammy is suggesting that Lengel's no-bathing-suit policy is a way for him to maintain power and control in his store.
I started to say something that came out "Fiddle-de-doo." It's a saying of my grandmother's, and I know she would have been
"I don't think you know what you're saying," Lengel said.
"I know you don't," I said. "But I do." (28-30)
You can imagine what Sammy was starting to say here before he wisely changed it to "fiddle-de-doo." In addition to showing Sammy refusing to be intimidated by Lengel, this scene suggests that his grandmother has helped him gain strength of character.
"You'll feel this for the rest of your life," Lengel says, and I know that's true, too, but remembering how he made that pretty girl blush makes me so scrunchy inside I punch the No Sale tab and the machine whirs "pee-pul" and the drawer splats out. (31)
Lengel tries to exert power over Sammy by using threats and intimidation. But Sammy's anger over Lengel's use of that tactic on Queenie overrides any effectiveness the threat might have carried.