Gears of War 2 (Xbox 360) - Achievement - Beat the Meatflag
Captured 10 meatflags (not Custom)
This achievement cannot be obtained in a custom match, however since the release of Gears of War 3, a new multiplayer mode was introduced in Gears of War 2 so that people could still play online with bots - The Social Xbox Live match. The achievement can be obtained in this mode.
The game type must be 'Submission'. The idea is that you down a neutral enemy and take him back to a specified location (the arrow at the top-left guides you to where you need to go).
The standard multiplayer bots in Gears of War 2 aren't always a pushover, so it may take some attempts. The game ends after 2 victories, so it will take a minimum of 5 games, but will likely take quite a few more due to the difficulty.