Host a game and set the time to 30 minutes and five flags on a game of CTF on the level Manor House. Have one person from each team saving the flag. To save the flag, a person has to recover the flag. The two other players go to the other team's flag and pick it up, the person getting the achievement then kills them and touches it and it will respawn, then the next person comes and does the same thing. This achievement can be obtained in under 15 minutes.
The person recovering the flag just stays at their flags and does not leave, the people getting killed keep going back to their assigned flag.
Note: You can not play 1 vs 1 ranked matches. Minimum is 3 vs 3!