Knock-Knock Jokes Were Made for Twins

One day in the not-too-distant future, your infant twins won't require feeding and constant care around the clock.  Back in those hazy days when our twins were teeny, I never imagined that one day I'd hear this at our breakfast table:

A: "Knock-Knock."

R: "Who's there?"

A: "Rain."

R: "Rain who?"

A: "Reindeer!!"

Both: "Ha ha ha ha ha ha ha!!" in that crazy way that only twins sharing a joke can replicate.  

Shared twin laughter is among the most beautiful things one could hear.