After ascertaining that Lawrence remembered how to play knock-knock, [Kennedy] said "knock knock."
"Who's there?" Lawrence dutifully replied.
"Iza."
"Iza who?"
"Iza ya next door neighbor."
Lawrence laughed while recounting the moment. "Iza ya next door neighbor. I can hear him say it."

According to Larry Newman, Kennedy "wouldn't listen to a dirty joke, especially if it was an ethnic joke. And especially if there was a mimicked accent involved. He would simply say 'I don't want to hear it' and walk away." Given this, his "Iza" joke becomes even more inexplicable. Was he smarting from the poor turnout for his motorcade? Upset that he appeared to be losing the support of blacks and backlash whites? Did it prove that his civil rights education remained incomplete, or could never be completed? That he would have been among the whites telling pollsters that they wanted blacks to have equal rights, but did not want them next door? Perhaps he considered jokes like this one simply, as he had told George Taylor about the practice of segregating his campaign workers at lunch in 1946, "one of the things of the time."