Whack a Zombie was a Flash Game part of PETA2 "Flesh is for Zombies" campaign, in the Game, you play a Whack-a-Mole type Arcade Game where instead of Moles you Whack Zombies.
There are from what i have played 3 Types of Zombies, a Normal Zombie, A Fast Zombie and a Zombie with Meat
you can see References to Two Other Peta Campaigns(Kentucky Fried Cruelty and McCruelty)