Fidget spinner
This year's winner

The latest fad
All schoolchildren had

To have

"We have to have it!", they exclaim,
"Last year's toys just aren't the same!"

A nine dollar trilobular spinning wheel?
Why would you need one? What's the deal?
"It demonstrates conservation, Dad.
Can't we PLEEEEASE get some?"

Conservation?

"Conservation of angular momentum"

So it's educational, eh?
Oh, okay.