10. A Whole Bunch Of TGIF Sitcoms
Here's a mind bender for you: half of the sitcoms you grew up watching, namely Family Matters, Perfect Strangers, Full House, Boy Meets World, and Step by Step all share the same universe. The thing connecting them? None other than Steve Urkel.
Yes, a whole bunch of shows airing on the TGIF programming block connect to one another and had funny little crossovers now and then. Starting with Perfect Strangers, Family Matters is actually a spinoff of that show, with Harriette Winslow first appearing as an elevator operator in seasons three and four. She then got her own series, which is what turned into Family Matters.
Family Matters quickly became the Steve Urkel show, and he showed up in a Full House episode called Stephanie Gets Framed, where he helps Stephanie deal with having to wear glasses. In the Boy Meets World episode Beauty and the Beast, Steve sends a chain letter to Cory and the two are apparently friends, though they don't interact on screen.
Then Steve also appears in Step by Step pretty brilliantly. At the end of a Family Matters episode, Steve flies on a jet pack through the roof of the Winslow house, and he lands in an episode of Step by Step, crashing in front of the Lambert-Foster family while they're on a picnic. Okay, that's awesome.