It's the classic invitation. A woman drops a handkerchief so that a man will retrieve it. There is something clearly communicated there. Today, it's not napkins, it's a slip of paper with a phone number on it, or a flower, or something that is actually dropped by mistake
so that in returning it you are saying that something about you is honest and good at heart, like Abe Lincoln
who was told to have walked miles to return a patron's change. Today, you'd be lucky to get a block away
I wouldn't mind a little old fashioned and probably cheesy attempt like that. There are only so many ways to strike up conversation with a stranger in public that aren't intrusive. If I were to drop something small and a guy revealed this to me, there would only be a split second to make eye contact before the entire moment was over, a window slammed shut that you can still see through.
The thing is that I seldom drop or misplace anything, or at least anything that could be returned to me before I left the scene, speeding off in my car or out the door before it's too late. And it's not like there's a gang of guys looking for me to drop something anyway. I have a hard enough time letting a guy pick up the check and that's when I know him. I'm doomed.