I've noticed a trend that when I have people in my studio - if you crack jokes, be silly, etc. right before a take, the take that follows tends to be a pretty good one, often the one you keep. There's even evidence of this effect with, I think it was a Miles Davis session? (seriously - I read an article on the internet about it sometime ago)

Not that it's a magic bullet that will work every time, it just helps. To me the sensation is that once you're all done laughing most people enter a more meditated focused serious state as a result of contrast.

This is in comparison to when musicians stay really focused on something trivial like avoiding a mistake or whatever and then they just keep screwing up more and more things - the whole so called "red light syndrome" (I hate that term!) I think taking a break to have a laugh is one of the easiest ways to reset mentally. And now I wonder if this effect could be used to help us prepare for performances too, or any other aspects of life.