Side Piping (Side-Pipe-Ing) - is:
1. When a man or a chick with a strap-on is fucking a man or tranny in the ass from behind (doggy style).
2. The person in the aft position grabs the other persons dick, pulls it back to where it is between the legs of the two people fucking.
3. Starts to jerk it off in the open space available. Being that the only available space in this fucking condition is to either side it is called Side Piping.
Dude - I was Side Piping that Thai tranny hooker while I was nailing her ass and that bitch blew a load on the coffee table and now we got jizz on the TV remote.
Tranny to tranny friends - That dude bent my dick around behind my leg and jerked it off while he nailed my ass. He made me cum but I think we should charge extra for Side Piping!
When a very attractive girl makes you journey down the left or right side of your pant leg. In other words she causes you to become erect down your pants which can be embarrassing and even painful if wearing tight jeans.
COLIN: OOOOO Im Sidepiping... three o'clock!
JOHN: Oh yah i see her. She's a beut'!
COLIN: Son of a... this hurts.
JOHN: Dude! Your bursting at the seams. shouldn't have worn those tight jeans. Stop shopping at Ed Hardy.
what becomes of a peenee in pants that are too tight.
cederic: jeez omar, your side piping is ridiculous.
omar: um, cedric, i know you've eaten a lot of shrooms
but you're package isn't looking so discreet these days either.
When a fellater moves to a side position on the cock to avoid getting a mouthful of jizz. see also "harmonicock"
She was not a lover of spunk but did not want to disappoint her lover, so she used the side-piping technique to take him across the finish line.