Level up any one character to level 50.
Complete the game in Extreme Mode
Destroy 1000 Crates
With Hit Girl, Kill 2 enemies in one wall run attack.
With Big Daddy, use the flashbang to stun 6 enemies at once.
Complete a level in Co-op
Collect all 8 hidden comic books
Complete the game in Normal Difficulty
Kill 1000 enemies
???
Set off the security camera 5 times in one level.
With Kick-Ass, Kill 10 enemies during one rage activation.