Due to the online feature of this game being all but dead you may need to find a boosting partner, you can create a gaming session here; http://bit.ly/gTa5Tf
, you'll need a total of 2 players to boost this game.
Now, for this achievement you need to win a ranked deathmatch by at least 5 kills, if you've decided to boost the game this is easy enough, it's a good idea to boost this achievement while boosting one of the others, for example; Are You Cheating? in TimeShift
or Bullets Are Expensive in TimeShift
Once you've completed the match the achievement will unlock!