Where in the hell did the phrase 'back in the day' spring from. I first noticed it in several Lee Child 'Reacher' novels where he seems to have a particular phrase in each of his many escapist novels that's repeated until you start expecting it on every page...almost. Now it seems to have descended into the common consciousness and it even graced the pages of last Sunday's Observer no less.
Perhaps someone will write an algorithim to calculate the next likely ocurrence in the literature or the next likely phrase. 'Yes we can' maybe.