Baby's first joke (I think)

Adriana came and found me while I was folding laundry.

DAD-WHERE? She asked, something she wants to know pretty much every day.

"Where do you think he is?" I asked. Usually she replies WORK, but this time she just repeated her question. "He's at work," I told her.

DAD-WHERE? Adriana repeated.

"Work," I said. We went back and forth a few more times, and finally I said, "I don't know, where is Dad?"

MOON, she signed. 

"Dad's on the moon?" I asked. She nodded, and then giggled so hard she had to sit down. For the rest of the morning as played with her baby or read books, she would stop every now and then, sign DAD-MOON, and collapse in a fit of giggles. Pretty soon I was laughing too, and I didn't even get the joke.