What is Harrison Ford's broccoli joke?

So this guy is working in the produce department in the grocery store and a lady walks up and says “Excuse me, where’s the broccoli? I can’t seem to find it.” He says, “Oh, I’m terribly sorry, we ran out of broccoli, we will have some first thing tomorrow morning.” So he returns to his work.
A few minutes later the lady comes back and says, “Mister, where’s the broccoli? Do you have any broccoli?” he replies with, “No ma’am we’re fresh out of broccoli, we’ll have some tomorrow morning.” And he returns to his work.
A few minutes later the same woman walks up right into his face and asks, “How come I can’t find any broccoli? Where’s the broccoli?” He says, “Lady, do me a favor will ya? How do you spell ‘cat’, like in ‘catastrophic’?” she replies with ‘C.A.T’. He says “How do you spell ‘dog’ like in ‘dogmatic’?” she says ‘D.O.G’. He says, “How do you ‘f*ck’ like in ‘broccoli’?” A little confused, the woman replies with, “There is no ‘f*ck’ in ‘broccoli’.”
“THAT’S WHAT I’VE BEEN TRYING TO TELL YOU LADY!”