Boomerang Fu

Connect 2nd controller
Select 2v2 with easy bots
Make sure friendly fire is on
Have 2nd controller kill main character every round.
Win or lose you will get the achievement at the end of the game

Simple!!

To get this achievement you have to be awarded the title "taken one for the team" at the end of a game.
You must play a group match as you need to be killed many times by your teammates.
The easiest way to do this is to play with 3 bots on easy mode ; it will be a 2 v 1 on your side.
Stay in front of the other player on your team at all times and when they shoot you'll get hit aswell.
Keep doing this during the match and you should get the achievement at th end of the match :)