It’s from The Onion. Tongue-in-cheek, y’know.
The Onion: “America’s Finest News Source,” 27 September 2000, More U.S. Children Being Diagnosed With Youthful Tendency Disorder
Youthful Tendency Disorder (YTD), a poorly understood neurological condition that afflicts an estimated 20 million U.S. children, is characterized by a variety of senseless, unproductive physical and mental exercises, often lasting hours at a time. In the thrall of YTD, sufferers run, jump, climb, twirl, shout, dance, do cartwheels, and enter unreal, unexplainable states of “make-believe.”
After much serious reading and thinking, you just need something silly.
posted by Valerie