A broken off beer or liquor bottle, (in some instances, a broken pool cue) used as a jagged weapon in a fight. Usually the person brandishing it is Irish, pissed off, and swings it around like a lightsaber.
I nearly got cut in the face with an Irish lightsaber when the soccer hooligans were rioting outside the bar.
by Dr. Claw February 8, 2009
Get the Irish lightsabermug.