Create a Custom Handgun.

Try to push something heavy with Rebecca.

Defeat an enemy with a knife.

Destroy a zombie's legs.

Defeat an enemy with a critical-hit headshot.

Attack an enemy to save your partner who is grappling with that enemy.

Defeat Stinger.

Complete The Green Sabre.

Capture 30 territories.

Win a race in Inside Track Betting.

Get arrested 50 times.

Take the train between cities.

Achieve 'sex' with any of the girlfriends.