These are Fidget Spinners®, and there were exactly 0 in my area on Friday. But suddenly yesterday, it seemed as if everyone and their grandmother had one, and today I saw a kid selling them like fucking drugs.
I got to use one yesterday when a kid lent it to me for a minute or two. I admit it was pretty cool; you hold it in between your fingers and spin it, and it keeps spinning for a while. I'm not exactly sure how it works because I didn't get a chance to inspect it carefully; all I know is that it spins for a while.
But that's not the point. The point is how did these get popular literally overnight?