He use it in a way that correlate earnestness as the quality that would be really for both being serious and being sincere.
So, rather than perceiving it as something 'serious' , we perceive it as telling the fact that we know all along the way it is with a little sense of comedy
I recently went on a scavenger hunt at the yorktown mall with a bunch of friends. It was really fun cuz we ate, shopped, and celebrated one of my friends birthday.
Hope this helped!
I believe that flashbacks could be used to slow the pace of a story. If you are telling one story, and then decide to introduce a flashback, that would only slow down the story you are already telling.