Left 4 Dead 2 on the Xbox is one of the first retail games to include avatar awards. There are 4 T-Shirts to earn and a med kit from the game as an avatar prop.
Left 4 Dead 2 T-shirt, Bull Shifters T-shirt and Med Kit, Depeche Mode T-shirt and Zombie Hand T-shirt
The awards and the method to unlock them are:
- Med Kit – “earned by beating all five campaigns”
- Bull Shifters T-shirt– “earned by winning 10 games of Versus”
- Left 4 Dead 2 T-shirt– “earned by winning 10 games of Scavenge”
- Zombie Hand T-shirt – “earned by killing 10,000 Infected”
- Depeche Mode T-shirt – “earned by rescuing Gnome Chompski from the Dark Carnival”
Hard and Soft Gaming 
how do you get four in the avatar customizer
You can’t. I used Photoshop to create a combined image.