Write an English composition on the topic of an interesting joke! ! ! ! !

My sister is a primary school teacher. One of her students told her that a bird has built its nest in a tree outside the classroom.

"What bird?" My sister asked.

"I don't see any birds, madam, only a bird's nest," the child replied.

"Then, can you describe this bird's nest for us?" My sister encouraged her.

"Well, madam, it's like your hair."