‘A monk asked, “I ask you to say something about that which is immediately at hand.”
The master said, “Pissing is an easy matter, I can do it by myself.”‘ (The Recorded Sayings of Zen Master Joshu)

Some zen masters like to be provocative – or down-to-earth – depending on how you look at it; Kodo Sawaki is a more contemporary one who frequently invoked bodily functions. But I don’t think Joshu is trying to shock the monk, unless it is to remind him of the intrinsic value of the ordinary. I have heard another version of this story (or perhaps a different story) where the teacher excuses himself after a question about the deep meaning of Buddhism, and says he has to pee: ‘such a small matter, and yet I have to do it for myself. Can you do it for me?’