Go to multi-player mode and use at least two players. Put two Carriers (the hovercraft) back to back. Get in between both of them and get in one. You will get stuck, and the game will show you in one carrier, but you will really be in both on them. The other person can shoot either the carrier or you, and you will get hurt. This is like a Voodoo spell. If you go in a robot and the other person shoots the vehicle for awhile, when you get out of the robot you will have no health but be invincible. While invincible, avoid health, committing suicide, or getting run over, as the effect will be canceled.