The ability to laugh at things that it's likely only the two of you (among all of the souls in the universe) will find funny.

Like this:

I was sitting on the edge of the bed, where my wife was snugly under the covers. I pretended I couldn't find her legs under the covers.

"Hey, where's the rest of you?!" I cried.

"Are you still carrying those legs around?" she replied. "I left them down by the tracks."

I'm still laughing.

Can any of you decipher this? We refer to it as a moment of Reagan zen, to give you a hint.