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

Extinction (Bronze): 100,000 Zombies killed. 
Paint The Town Red (Bronze): Fill the screen with the maximum amount of blood 
on any level. 
Red Shirt (Bronze): Kill the away team Zombie. 
Hot To Trot (Bronze): Last 30 seconds with 50+ zombies on fire. 
Murder On The Dance Floor (Bronze): 1000 Zombies sent dancing. 
Brain Surgery (Bronze): 100 Brains sucked. 
Texas Style (Bronze): 100 Chainsaw Combos. 
Dynami-Te-He (Bronze): 1000 Zombies blown up. 
Graduation (Bronze): Complete Zombie Academy. 
Tourist (Bronze): All Arcade levels unlocked. 
d6 Commends You (Bronze): All Bronze medals. 
d6 Respects You (Bronze): All Silver medals. 
d6 Admires You (Bronze): All Gold medals. 
Friend of Bruce (Silver): All levels unlocked. 
Friend of d6 (Gold): All Developer medals.