[masraum]

I think "like" replaced "um" as a way to give folks a moment to think of the next thing that they want to say.

And most folks in society want to fit in, so they mimic the other people around them that they want to fit in with. So once one person does it it spreads to others. I think some folks are VERY likely to mimic and other folks are less likely to mimic. It starts by infecting the more likely to mimic but then once enough folks are doing it, the less likely to mimic start because a much larger portion of the group that everyone wants to fit in with is now doing it.