I remember hearing when I was younger that there was this show called
St. Elsewhere and that people hated the ending.
I only just found out now what the ending was: in the last episode, it was revealed that the entire series had taken place in the mind of an autistic child. That's a serious cop-out. But here's where it gets good: because of the way that TV folks like to have characters from one series make cameos on others, more than 150 other television shows (including many of TV's most-loved series from decades ago) can all be argued to have taken place within this one autistic kid's mind. Read this. (Halfway down there's a plain-text copy of the list.)
I bet if I watched more TV I would find this less charming. As it is, I imagine an enormous butterfly somewhere that dreams it is a television.