What's so funny about the barber in "Tunnen"

This is a joke, you can understand it as soon as you read it. The following translation is attached for your reference:

Tunin

original text

As soon as I was asked to shave someone's head, I raised my hand and was hurt. But he stopped the knife and said to his master, "this head is still tender, so I can't cut it." And after a while, I will shave when I am old. "

translate

A barber shaved someone's head. At first, he shaved a few times, and then he hurt several scalps. So he put down his knife and stopped shaving. He said to his master, "Your scalp is too tender to cut. After a while, let it get older and shave you. "