The act of lubing up the tail pipe of a motorized vehicle and maneuvering oneself in the position to have sexual intercourse via tail pipe. Often this act is scorned upon and rarely executed, but when done, can be a very enjoyable and kinky experience. Best if done when said vehicle is of high class. Also, if tail pipe is large enough, two partners can double penetrate the tail pipe. Known as slonkpiping.
A) Hey! You want to go slonkpiping with me?
B) Yeah sure. I love stuffing my rod in vehicle assholes!
A) I heard Ted is a slonkpiper.
B) Gross! I can't believe i let him stick it in me.