Why A Duck?

There's
a "quack" at Bronx High of Science that triggered the memory of this routine.
A transcript of some of the routine

HAMMER: Do you know what a lot is?
CHICO: Yeah, itsa too much.
HAMMER: I don't mean a whole lot. Just a little lot with nothing on it.
CHICO: Any time you gotta too much, you gotta whole lot. . .
HAMMER: Come here, Rand McNally and I'll explain this thing to you. Now look, this is a map and diagram of the whole Cocoanut section. . .Here's Cocoanut Manor. Here's Cocoanut Heights. That's a swamp; right over there where the road forks, that's Cocoanut Junction.
CHICO: Where have you got Cocoanut Custard?
HAMMER: Why, that's on the forks. You probably eat with your knife, so you wouldn't have to worry about that. . .Now, here's a little peninsula, and here is a viaduct leading over to the mainland.
CHICO: Why a duck?
HAMMER: . . .I say, here is a little peninsula, and here's a viaduct leading over to the mainland.
CHICO: All right. Why a duck?
HAMMER: I'm not playing Ask-Me-Another. I say, that's a viaduct.
CHICO: All right. Why a duck? Why a--why a duck? Why-a-no-chicken?
HAMMER: I don't know why-a-no-chicken. I'm a stranger here myself. All I know is that it's a viaduct. You try to cross over there a chicken, and you'll find out why a duck. It's deep water, that's viaduct.
CHICO: That's why a duck?
HAMMER: Look! Suppose you were out horseback riding and you came to that stream and wanted to ford over there. You couldn't make it. Too deep.
CHICO: But what do you want with a Ford when you gotta horse?
HAMMER: I'm sorry the matter ever came up. All I know is that it's a viaduct.
CHICO: Now look. . .all righta. . .I catcha on to why0a-horse, why-a-chicken, why-a-this, why-a-that. I no catch on to why-a-duck.
HAMMER: I was only fooling. They're going to build a tunnel in the morning. Now, is that clear to you?
CHICO: Yes, everything---except why-a-duck. . .
HAMMER: And then, there's a little clearing there, a little clearing around it. You see that wire fence there?
CHICO: All right. Why-a-fence?
HAMMER: Oh no. We're not going to go all through that again!