In a multiplayer battle, obtain a chargeable weapon (Strike Rifle, Warp Pistol, Deatomizer) and charge it up, then press the pause button. You will hear a firing noise, but there won't be a bullet (although ammo will be depleted). After unpausing, a small remnant of light will be leftover on the gun. It will not be apparent to opposing players and will stay with you until you get killed. It does nothing to enhance gameplay, whatsoever.