Here is a sample:
Hui Neng once approached a student who was sitting in meditation. “Why do you spend so much time sitting?” he asked. “Because I want to become a Buddha,” the student replied.
At this, Hui Neng picked up a brick tile from the floor, and began rubbing it with his robe. “Why are you doing that?” asked the student. “Because I want to make a mirror,” Hui Neng replied.
“But Master,” said the student, “no amount of — oh, wait, I get it! Very funny, very funny.”