I don't know where everyone else got there definitions for laying pipe. However laying pipe is simply fucking the hell out of a girl.
Will;what are you doing this weekend
Guy;probally laying pipe to my girl.
Doing a great big dump that renders the toilet unusable for the next hour due to pungency.
"Where's Tim? He's been gone for half an hour."
"He's laying pipe.
the act of sticking your hog into a swamp donkey
who laid pipe last night? i laid pipe last night
Man, I was laying pipe with this one nasty chick last night and she farted and cried at the same time.
when a girl sleeps with a guy with a large penis
Damn, I'd heard Joe be laying pipe
A term used in TV writing. It's things that you wouldn't actually say in life, but they say it on TV to help you understand what's happening in the story.
A character saying, "You're my sister and I love you...", so that we understand that she is the character's sister is laying pipe.
(v) To take or the act of taking a shit. Specifically a large, cylandrical, log-like dump.
"I was laying some serious pipe on the shitter."