"This is J.D. Salinger," I say, pointing to Jerry as if he were a trophy I was delivering.
"Yeah?" says the clerk, her face coming alive. "Really?" She looks at both of us for the first time, smiling.
"It's a pleasure to meet you." She extends her hand to Jerry. "You used to work for Kennedy, right?"
"Indeed I did," says Jerry, his eyes plashing across mine, mischief rearranging the kindly lines of his face. To keep from laughing, he turns away.
"Did I say something wrong? says the cashier.
"He was very fond of Jack," I reply.
Of course, none of the students got the joke, so I had to explain that the cashier had confused Jerry (as he prefers to be called, at least in the novel) for Pierre Salinger, JFK's press secretary. I explained that this was a literary technique called allusion, a reference made, usually indirectly, to a fact outside the text which the reader is simply expected to know. I gave another example, which I usually use; a line from the film A Few Good Men:
"Three cases in two years?! Who's she handling, the Rosenbergs?!"
I pointed out that if you don't know who the Rosenbergs are, you won't get the joke.
Inevitably, someone asked, "Who are the Rosenbergs?" I replied, "Look it up; Julius and Ethel Rosenberg." The next question ... wait for it ...
"Weren't they on I Love Lucy?"