Entered the Dragon
Complete level 1 in solo mode.

This thing of ours
Complete level 1 in co-op mode.

Sik, Bro
Kill Kim Bong Sik, without getting hit by his projectiles.

Robbed the grave
Kill Teniu the Grave, dodging all the crates.

Kill Bloodshot avoiding all his melee attacks and slapping his face everytime you can.

Made man
Complete the last level in solo mode.

A good earner
Find and shoot all the hidden objects in the game in solo mode.

Perform 3,000 headshots in solo mode.

Perform 200 nutshots in solo mode.

Get a 4 Star global ranking at the end of all levels in solo mode.

Complete the last level in Crazytrain difficulty.

Down boy
Kill 20 enemies with a chihuahua on your leg in solo mode.

Keep quiet
Kill the screaming enemy in all levels in solo mode.