That was funny

Two math professors are in a restaurant. One argues that the average person
does not know any math beyond high school. The other argues that the
average person knows some more advanced math. Just then, the first one gets
up to use the rest room. The second professor calls over his waitress and
says, “When you bring our food, I’m going to ask you a mathematical
question. I want you to answer, ‘One third x cubed.’ Can you do that?”
The waitress says, “I don’t know if I can remember that. One thurr…
um…”
“One third x cubed,” says the prof.
“One thir dex cue?,” asks the waitress.
“One”
“One”
“Third”
“Third”
“X”
“X”
“Cubed”
“Cubed”
“One third X cubed”
“One third X cubed”
The waitress leaves, and the other professor comes back. They resume their
conversation until a few minutes later when the waitress brings their food.
The professor says to the waitress, “Say, do you mind if I ask you
something?”
“Not at all”
“Can you tell me what the integral of x squared dx is?”
The waitress pauses, then says, “One third x cubed.”
As she walks away, she stops, turns, and adds, “Plus a constant!”