the main vein 

Penis

My bladder is so full I think its time to drain the main vein

the main vein by Xeroman January 31, 2016

Drain the main vein

Slang for "Urinate"

"The Main vein" being the penis of course.

"I gotta drain the main vein something fierce"

Drain the main vein by Doc Evil July 24, 2003

Rail the Main Vein 

To snort a line of cocaine off of a fully erect penis

Me: Yo, do you even rail the main vein?
12 year old on Xbox live: Yeah, fucker, I rail the main vein every day!

Rail the Main Vein by Blawkz February 9, 2015

To drain the main vein 

Expression: for guys to take a piss.

I need to drain the main vein...like right now. Is there an industrial area where I can do it on the street?

To drain the main vein by Uncle Dimma July 26, 2025