Forge-less Halo 3 glitches?

[RedCrossRobbery]

alright, so I've been looking for some fun Halo 3 Glitches that me and my buddys can mess around with. Just fun little places to get in, out, or above of. Problem is, whenever I look them up, they always show me glitches you can do while in Forge mode. I used to glitch in Halo 2 alot, and LOVED it, and the ridiculous invisible walls in Halo 3 made me completely hate the game, but I'm giving it another shot, and am wondering if anyone knows of any good glitches you can do? Any secret rooms you can get to? or how to get above or under any maps?
Allow me to add I know bungie bans, I DO NOT want to use these for matchmaking, Just fooling around with friends :]

 

[Ryan I]

DONT GLITCH!!! HALO 3 IS ALOT DIFFERENT THAN HALO 2!
You will be smacked with the Bungie BanHammer...You wont be able to play!