Stand in front of the Troika (turret) and then switch from your lancer to another weapon. As you're doing this immediately press "X" two times (get on and then off troika).

Then shoot once and switch back to the lancer and immediately press "X" two times (get on and then off troika). You have now done the glitch and everyone else will see you holding the weapon you had switched to while you will see yourself holding the lancer. For the remainder of the ammo in your current magazine it will appear on everyone else's screen that you are shooting really fast. You do not see this rapid fire and it will stop once you reload.

Now, when you chainsaw someone it will appear on their screen and everyone else's that you only melee them with the weapon you had chosen. They'll then be going through the animation as if they are being chainsawed, and they will SURVIVE.

After chainsawing someone, if you press "B" to rev your chainsaw, the person you had chainsawed will instantly explode. If you switch to another weapon and then back to the lancer, the person will explode. Also, if you get hit or die either from friendly fire or an enemy, this will cause the person who was chainsawed to explode. It's sort of a self destruct failsafe mechanism build into the glitch.

Once you have chainsawed someone there is no time limit for when you can cause this person to explode. It lasts the entire round in Multiplayer or the particular section you are playing on in Campaign as long as there isn't a cut scene. You can only do this glitch to one person at a time since pressing "B" to chainsaw another player would instantly cause the first player you chainsawed to explode. Host cannot do this glitch.

Side Effects:

- Shooting a weapon on your back happens when you do the glitch and then switch from the weapon in your hand to another weapon and then back again. Switching to another weapon and then back again will put the gun on your back on everyone else's screen and they'll see it shooting whenever you press "RT".

- Shooting a gun in the vertical position at your side happens when you do the glitch when the lancer isn't the first weapon in your hand or isn't in your inventory when you start the glitch. So the first part wouldn't start out or have to involve the lancer, but rather another weapon.

Today's hilarious glitch video: Gears of War remote controlled exploding enemies [Joystiq]