Easier mongoose mowdown achievement
You need a headset to do this. Simply find somebody else with a headset in matchmaking and ask them to let you run them over in exchange for them killing you to get an achievement. Don't sound like a jerk though or they won't do it. This is an I help you, you help me sort of thing!
More tricks, tips and cheats for this game are right here - Halo 3 cheats
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