The Hammer Slammer

Tutorial: THE HAMMER SLAMMER - In forge mode (or any other mode that you have access to a mongoose and gravity hammer) turn over a mongoose so it is upside down. Jump on the mongoose and then crouch. While crouching take out your gravity hammer and press the R Trigger (Fire button). If done correctly you should fly into the air

The Butterfly Halo 1,2 or 3

Using the BattleRifle and a button combo you can launch an opponent as high into the air as you want. As long as you continue pressing the buttons they will continue to rise, the glitchy part is that no damage will be done to the opponent.
Tutorial: The Butterfly - Grab a Battle Rifle and then fire once. Press the RB button (Right Bumper) and then quickly press the melee button. Keep doing this sequence fast while under an enemy and they should (If done correctly) "float" up in the air for as long as you continue to do the glitch

halo 3 skull

Grunt Birthday Party Skull Effect: When you get a headshot on an enemy Grunt, they will explode into confetti, and you’ll hear children cheer, “Yay!” in excitement.

Grunt Birthday Party Skull Location:

This is one of the more fun Silver Skulls in Halo 3. The “Grunt Birthday Party Skull” is located on the second mission, “Crow’s Nest”, just before the area where you team up with the Arbiter (it’s the piping area where you see Drones buzzing in and out of an array of pipes). Just before you jump down the pipe to meet up with the Arbiter, stop at the ledge, and look directly below you. Along the wall that you drop down, there is a small ledge with a green arrow pointing backwards. Jump onto this ledge (rather than all the way down), and go inside this secret room. The skull is in the dead center of the room.

Unlimited turret guns

Note: this cheat can only be done in Forge mode.
Start a game on any map that has turrets with two players (more if you wish).
Now have one player go find or add a turret, then have that player get on it.
The other player should go into editor mode (flying bot) and grab the turret while the other player is still on it.
The player on the turret should now press B to rip it off. There you go! Notice how the turret on the stand is still there even though you have it in you hands?So the other players can get the turret again.

halo 3 forge glitch

Start up a forge local slayer match (this works on live but its very hard unless two people have a great connection) have a monitor player and a spartan or elite player. have the monitor spawn a weapon and have the other character spart/elite pick that same weapon up at the same time the monitor does dont let go after the other player has it in their hands. the weapon is invisible and their arms or hands should be in an awkward position while in monitor you can move around the weapon which move the players arms and hands into other funny positions (DO NOT USE THE SNIPER RIFLE ON THE PIT LEVEL IT FREEZES THE GAME)