The Illegal flash is often used in the online First Person Shooter "Counter-Strike" To do this you throw a flash grenade inbetween two boxes, and it glitches, flashing everyone inside the "upper B-bombsite" tunnels. It works well if you have two people, one to flash, and the other to run into the tunnels and kill everyone there.
by Lovemachine July 20, 2008
Get the Illegal Flashmug.