Nothing new under the sun?

I thought up an idea for an extreme sport a long while back. My fictional sport involved jumping onto the tops of cars on a freeway, unknown to the drivers. I called it car surfing, and thought it was a pretty cool concept.


Then I found out that it already existed. The actual real-life sport of car surfing doesn't involve moving across cars, but instead just preforming "various stunts, including hanging out of the car or 'surfing' on the hood", but it's still really close to my fictional version. Apparently, I can't come up with a sport extreme enough not to have already been tried. 


Not only that, but they also have train surfing and elevator surfing.