Urban Dictionary: Drain the main vain

1. The act of releasing urine from your penis.

2. The act of releasing semen from your penis

I drained the main vain all over her.

Well, time to drain the main vain

by Nttm May 12, 2010

as in you need to go urinate(av a piss).

B: aw ive drunk too much. coming to drain the main vain?
C: yer sure...

by gareth matthews January 28, 2007