The act of having vigorous sex on the open tailgate of a truck until the tailgate breaks and falls off.
We was giving each other an Appalachian tailgate smasher on the Ford and the tailgate done fell clean off after five minutes!
When there is a line of cars behind one person driving slow, and you're somewhere several cars back so you tailgate the person in front of you, who tailgates the person in front of them and so on and so forth until someone is tailgating the slow driver.
Joe: Man, I was five cars back from some old granny today and I couldn't pass... it sucked.
Pete: Dude, you totally should have tried vicarious tailgating.