You've gotta laugh with them.

Juliette: "How does a fish walk?"

Me: "A fish doesn't walk! That's silly!"

J: "Maa-aaa! I'm trying to make a joke!" she reprimands.

Me: "Oh. I'm sorry. How does a fish walk?"

J: "Bare foot!" Giggles. "How does a fish walk?"

Me: "I don't know. How does a fish walk?"

J: "You have to put shoes on!" More giggles. "How does a fish walk?" she asks again.

Me: "I don't know Juliette. How?"

J: thinks for a minute... "Underpants!" She and Cosette giggle hysterically.

Cosette: "Mommy, what if I put a fish on the table?"

Me: "I don't know. What if you put a fish on the table?"

C: "You have to give it dinner!" Laughs.

J: laughing "Cosette, I'm laughing!"

C: "You have to give it dinner!"

J: "Underpants!"