Call of Duty World at War Der Riese Glitch?

While online about 30 minutes ago, I came across a guy doing a glitch. From the beginning area of Der Riese, this guy floated through the walls to the electricity, linked one of the teleporters, and when he came back had many upgraded guns. He dropped them all over the ground which allowed the other three of us to pick them up as we please. If anyone can let me in on how to do this as I was disconnected from Xbox Live before being able to ask him myself. Thanks.