Win an Episode as part of a party of 3 or more players

Bump into 3 people while rolling on the ground before getting up

Get first place in a racing round

Qualify from your first round

Complete Campaign Mode In Co-Op Mode

Complete Campaign Mode On 'Normal'

Complete Mission 9 (Any Difficulty Level)

Blow Up 1 000 Zombies

Complete Mission 6 (Any Difficulty Level)

Complete Mission 4 (Any Difficulty Level)

Complete Mission 3 (Any Difficulty Level)

Perform 500 Headshots

Fully Upgrade All Stats Of Any Weapon In Campaign Mode