You will need three people for this glitch. First open the help room and then go back into the first room.

Then two people get as close as they can to each other holding gernades. When they are both down they both point at each others chests with the pistol.

The person that wants to get the weapons must point at the other players chest while holding down X first then LT. The other player is still pointing at his chest.

When the person is revived he should instantly revive the other player right next to him (BE SURE TO STILL HOLD DOWN X AND LT).

When you are done reviveing him you should have no weapon. Go to the box for weapon and take it. w

This works 80-90% of the time. You can do this as many times as you want.