If you are "of a certain age" you may remember when "crossover" wasn't the marketing department's description of a station wagon with a tall body. Or a pickup truck with a weird amount of seats.
Crossovers are the television episodes that happened when Magnum P.I. left Hawaii and visited Simon and Simon in San Diego.
Or when Worf visited Deep Space 9.
Or that time when the Drummonds visited Mrs. Garrett at the Eastland School For Girls.
Or when Sonny and Cher visited Scooby, Freddie, Daphne, Velma, and Shaggy.
Or when the Brady Bunch visited The Partridge Family.
Oh, wait, that last one never happend, that was a Saturday Night Live episode.
Crossovers don't seem to happen as much any more, except in automotive circles because, clearly, the world needs a BMW slightly bigger than a 5-series, but slightly smaller than an X5.
Reality TV shows which should have a crossover
Mythbusters and Jackass
Don't you want to see Jamie Hyneman trying to make sure everyone adheres to safety standards. Would the Jackass guys beat up Adam because he is fundamentally geeky, or would Kari, Tori and Grant be able to stop them? It could end up like an episode of MacGyver.
Mantracker and Survivorman
You could do it over a couple of episodes, Mantracker hunts Survivorman after Survivorman is abandoned in the Amazon/on a deserted island/in Paris. I imagine it would end with Mantracker finding Survivorman on day four and Survivorman eating Mantracker's horse, because he was starving.
Holmes on Homes and Canada's Worst Handyman
I imagine poor Mike trying to stop the contestants from doing stupid things in different locations all at the same time. And chastising Andrew Younghusband for letting them do something stupid with little or no supervision.
The Apprentice and Jon and Kate Plus 8
Wouldn't the Donald look like a jerk firing one of the kids every week? On the other hand, I'm pretty sure Mady would come out as the apprentice.
Dog the Bounty Hunter and What Not to Wear
Because, you know, have you seen what they wear? Clearly Clinton could use some hair advice from Dog. Stacey could use some help from Beth too, and maybe a push-up bra.
American Chopper and Trading Spaces
You know the OCC guys would come up with something cooler than any of the designers on Trading Spaces. But would would the Trading Spaces designers do to the OCC shop? And would Mikey be able to keep Paul Sr. from killing them?
Punked and Overhaulin'
This would come out like an Agatha Christie mystery. Or a Sherlock Holmes mystery. Oh, no, it would totally be a Ray Chandler mystery! Ya know, because they're shot in California and everything. The entire episode would be about who stole what from whom and where they're hiding it and whose side is Chip Foose really on?