Illusion Speed Bump - Pavement Patty

Back in the day, a group of  concerned volunteers at concerts/festivals were deputized to roam about looking for those of us who might be ODing or in the throes of a bad trip.  I imagine many of these inherently empathetic folk went on to become EMT's, nurses, mid-wives and even the occasional internist or two.

But the way they went about it was pretty annoying.  What they would do is suddenly pop up out of the dark from right behind you, typically with a super bright flash light, calling out, "Acid Rescue!"  I mean, imagine if you just bought a bucket of pop corn at the ball game and then suddenly, without any warning whatsoever, someone suddenly screams, "HEY! COLD BEER HERE!"

You'd spill your popcorn, wouldn't you.

In general, if you were not tripping just before one of these apparitions, you damn well were afterwards, and it was usually a bad trip.

Which is a long way of saying that this method of speed control you cite is probably going to bring up some vaguely familiar feelings and emotions in drivers who might have done a little lsd back in the day, if not an out and out flashback.