This glitch can only be done in Danger Canyon for Halo PC.
First of all, make a gametype that includes Team Play = ON and Friendly Fire = OFF.
Start the map and the gametype (oh and it need warthog).
Have somebody join you then in the same team be behind the base at the rock wall then have the other guy ram you into the wall (like guardian kill in Halo 2) but you wont die you will end up on the opposite base.
Works on both bases.