"I can do that in my sleep"

You know that old term " I could do that in my sleep"?
Apparently it is true, as I can be humorous in my sleep.
Here is how my wife recalled it (I can't remember, I was asleep)
Jana (waking me up): "Leigh you're dreaming."
Leigh (in my sleep): "I know, I'm McDreamy"

Then I went back to my dream. I can tell jokes in my sleep.