We're in for Some Chop
From Halopedia, the Halo wiki
We're in for some Chop is a Halo 3 multiplayer achievement. It is awarded for destroying an enemy vehicle with equipment (e.g. a Trip Mine) in a ranked playlist or in campaign. It is represented by a yellow eight-pointed star on top of a red eight-pointed star. On top of this is a red circle with a white dash across it.
This achievement is currently impossible to get in a ranked playlist with a mine since it doesn't spawn in any map naturally except Sandtrap which is found only on Social Playlists.
The name is a reference to a line from the movie Aliens.
One way to get this achievement is to go to Tsavo Highway, disable a Brute Chopper (when there is a Brute in it) with a plasma pistol or Fuel Rod Cannon (aim for the wheel), throw a trip mine at it, and fire another overcharged shot at the Chopper. It will not reactivate in time to get away from the trip mine's explosion. Another easy way to get the achievement is use the power drainer on a Grunt inside a Ghost, or a Trip Mine on any of the vehicles in the first Prowler battle of the level The Covenant.
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