A sticky back ride is when you nut on a girls back while she's sleeping, put some kind of animal on her, and whenever she wakes up she'll have the animal stuck to her back.
Hey Tom, I just busted on this chicks back and practically gave her pet hamster a sticky back ride! She didn't even realize it until it got unstuck and crawled into her asshole.
A Twiggy-Back-Ride is when someone gives a drunk individual a piggy-back ride to their car or house to ensure they get there safely, and the drunk person involuntarily urinates on the back of the ride-giver.
"Man, I tried to do a nice thing and carry this wasted girl back to her apartment, but as soon as I felt this warm moisture on my back... I realized my good deed had turned into a Twiggy-Back-Ride."
When a grown black male lets an underage kid ride him piggy back style naked while singing a Justin Beiber song. This sexual act is highly illegal and frowned upon.