Charlie Murder

This is Rex's personal achievement. Once you level up you can select a skill to lift heavy things....such as Arcade Cabinets. Use one of these to crush your enemy.

Start a new local match. Select "Rex" as your player.

Play through the game as you normally would. When you "ding" and become level 2, press Left on your directional pad and unlock the ability "Massive Lift". (You'll need to be out of combat to do this.)

After clearing cars with a grenade and killing your first boss, you'll enter a bar with some arcade machines at the entrance. Pick one up using "X" and throw it at one of the approaching ninjas. If you've throw it and downed the target successfully, the chievo will pop.

Done.

Hey guys and girls
I just stumbled upon an easier way of getting this with no hassle at all
-Beat the easy boss that appears
-Kill the first group of ninjas and other dudes in the first building you enter.
-You will then be in an area that has "grenades inside" written on the wall and you will see 2 arcade machines just to the left where you entered.
-Pick one up, and go to the door and hold x to open, you will notice when you enter the bathroom with the machine still in your hand, and luckily enough there are 2 enemies sitting there, so you get an easy target :)