Stay calm William

I just got back from shopping in a local grocery store. I have to tell you this, I was behind a grandfather and his badly-behaved grandson. He had his hands full with the child screaming for sweets, biscuits, all sorts of things.
The granddad is saying in a controlled voice: “Easy, William, we won’t be long . . . easy boy.”
Another outburst and I heard the granddad calmly say : “It’s okay William. Just a couple more minutes and we’ll be out of here. Hang in there, boy.”
At the checkout the little horror is throwing items out of the grocery cart. Granddad says again in a controlled voice : “William, William, relax buddy, don’t get upset. We’ll be home in five minutes, stay cool William.”
Well, I was really impressed, so I went outside to where the grandfather is loading his groceries and the boy into the car. I said to the Grandad “It’s none of my business, but you were amazing in there. I don’t know how you did it. That whole time you kept your composure, and no matter how loud and disruptive he got, you just calmly kept saying things would be okay. William is very lucky to have you as his granddad.”
“Thanks,” said the Granddad. “But I am William. The little bastard’s name is Kevin.