Top definition
Penis.

Slang word for penis.
"Be right back, I'm gonna go drain the main vein".

"I drilled her with my main vein".
by mickyxtee May 09, 2009
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2
The largest vein in the penis. Once the penis has become erect, the blue/purple vein becomes clearly visible.
"Seeing that chick naked got me so hard that my main vein was just bulging!!"
by PMchoisi June 08, 2009
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3
The large vein that travels the length of a cock. Instrumental in delivering blood from the central artery during erection.
My cock was so hard, my main vein was swollen with blood.

I saw my heart beat as the main vein of my cock pulsated with blood.
by Tony from the Lido September 21, 2011
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