This is a Viral achievement. Someone in your lobby will need to have the "Exposed" achievement in order for you to unlock this.
A ranked match requires at least 4 players to launch. No one plays this game online anymore so you will have to set up a boosting session or find some friends to help you unlock this achievement.
From the main menu go to (Versus - Xbox LIVE Ranked Match - Host a Ranked Match) and then change the settings to:Game Mode:
Any game type will work, but Capture the Flag is probably the fastest. Simply capture the flag 3 times for your team to win and the achievement should unlock. If that doesn't work, try Deathmatch. Just make sure you have the most points at the end. That's how I unlocked this achievement.