Go into multi player mode and go to frag tag. Go to the stage 
Sneaks N Ladders. Climb the highest ladder and go to the big 
hole. Stand in one of the corners and walk very slow toward it. 
Keep walking until you fall. Make sure you stop walking when 
you fall. If you do this correctly you should be standing on 
thin air. You can look around to make sure nothing is under 
you. Now jump and you should warp to the bottom level. This 
trick is good when you are trying to get away from the other 
player.