While walking through the living room, my calf brushed an open box, leaving a scratch. It hurt, so I said "Ow!" The boy asked what happened, and I explained.
Then quietly, I said to the Elder Wendall, "So is this the true definition of a box cutter?"
He laughed. A moment later the Younger Wendall called out from the other room.
"So was it a box cutter?"
He probably thought his joke was much funnier than it really was, because we were laughing quite a bit.
Then his father asked, "What are you two, related?"
"Since the day I was born!" yelled the boy.