when two or more guys (or girls) get out their penises (hard or flaccid) and duel with them. This usually consists of the competitors smaking their knobs together - kinda like 'knuckles' - until one quits or submits.
HARDCORE GAMERS may involve household objects in their game, playing until blood is drawn.
Some items used are:
Barbed wire, paint thinner, lit matches and gasoline, sandpaper and lime, superglue and glass shards.
Man, me and Jim had a penis war last night...I bust him open pretty bad. He's gonna nedd stitches on his shaft.
A contest of wills fought by two men slapping their dicks against one another until one man becomes erect, at which point he loses, because he is gay (no offense.)
Often accompanied by the chant, "1-2-3-4! Let's have a penis war!"
Tom: "Did you hear? Ryan and Raul are going to have a penis war."
Brent: "I'm pretty sure that means they're BOTH gay."