Term used in video games, almost always in the first/third person shooter genres. 'Play the objective' means, in an objective-based game type, (where the winning condition will be achieving said objective instead of accumulating sufficient kills) focusing on accomplishing the objective, instead of "K/D Whoring," or focusing on having as large of a Kill/Death ratio as possible by the end of the game.
Alan: Hey man, why don't we go play some multi-flag in Halo?
Bob: That depends. Are you gonna be a K/D whore again, or play the objective?
Alan: What does that mean?
Bob: The first one means that you're playing for yourself. The second one means that you're playing for your team.
Alan: Uh...Can I do both?