What is "forbearance without desire"?

This is a joke, right? The contents are as follows ..

A studious boy asked a knowledgeable female professor for advice!

The boy said, "Excuse me, what does it mean to be tolerant without desire and righteously?"

The female professor replied very learned: "The first half of the sentence means that no matter how good a girl is, she can't arouse our desire ..."

Before the female professor finished speaking, the boy blushed and said, "Thank you, Professor, I know the second part."

[explanation: big is just = women have big breasts and men are very strong below. ]