Trophies - Successfully complete one of the following tasks to get a trophy:

Bully (Bronze): Take down one opponent.
Acrobat (Bronze): Perform a two stunt combo.
Adrenaline Junkie (Bronze): Stay in adrenaline mode for 30 seconds.
Hoarder (Bronze): Unlock half of all unlockables in career mode.
Hangtime (Bronze): Hold a stunt for 2 seconds.
Big Air (Bronze): Stay airborne for 3 seconds.
Backflip (Bronze): Perform a backflip.
Frontflip (Bronze): Perform a frontflip.
Woodcutter (Bronze): Collide with 3 trees in a race.
Crowdsurfing (Bronze): Collide with the spectators.
Friendly (Bronze): Invite someone to a race.
Roadrunner (Bronze): Lead a race from start to finish.
Berzerk (Silver): Take down three opponents in a row without crashing.
Pack Rat (Silver): Unlock all unlockables in career mode.
Stingy (Silver): Collect $50000 in career mode without spending them.
Frozen (Silver): Hold a stunt for 4 seconds.
Untouchable (Silver): Win a career race with your sled intact.
Head Splat (Silver): Land on top of another player in an offline match.
Rampage (Gold): Take down four opponents in a row without crashing.
Wire Fu (Gold): Perform a three stunt combo.
Boostaholic (Gold): Stay in adrenaline mode for 60 seconds.
Orbit (Gold): Stay airborne for 5 seconds.
Double Backflip (Gold): Perform a double backflip.
Double Frontflip (Gold): Perform a double frontflip.
Online Acrobat (Gold): Achieve 20,000 stunt points in a single online match.
Platinum (Platinum): Collect all other trophies.