All The Angry Mennonites/Billy Graham - Take 2

On the recent ride down to Maine, during one of the silent periods (when we took a break from theaudiobook), a large bright bus sped past us. Painted on the emergency exit door, in large balloon letters, was, “HONK IF YOU LOVE JESUS!”

“So are you going to honk?” asked my wife.

“I might,” I admitted. “If I knew which Jesus he's referring to.”

Why is this man laughing?