DS4 and I have a game where we'll go back and forth for a while like this:

"I love you"
"I love you too"
"I love you three"
"I love you 40 million" etc...

Usually it's just random numbers until we get to billions of googols or infinity. But yesterday, it went like this:

DS: "I love you 11"
Me: "I love you 22"
DS (catching on): "I love you 33"
Me: "I love you 44"...

We went all the way to 198 before I had to skip ahead to a million--mental math was never my strong suit. :-)