you need the "semi auto sniper" invisible weapon. has to be equiped in first "top" weapon slot, saved then when you join a game or make a new game you then hit triangle a few times till you see yourself holding no gun and your character in front of you "torso".

you are now invisible

now switch your weapon using triangle so you don't see "torso" if you don't want to see it.

be careful because if you throw it without unequiping it first, after you cycle your weapons making you invisible your game will freeze along with the others in the game...

so make sure you unequip b4 you throw it down....

and make sure you have a modded shield... because if you don't and if you get downed you will not die and no one can revive you...

if you have a ps3 i will add you and give you the weapon,
i got it from my buddy

i have over 700 mods, shields, guns, class mods, and grenade mods.
45 different mod shields.
5 diff weapons to shoot through any mod shield
and death mods including negative shield to mess with people, and class mod with negative team health regeneration.