An easy way to get this is to carry a weapon of some sort (I was using a spiked bat) and a few things of alcohol (beer, vodka, etc.). I was hitting a survivor with the bat, giving him alcohol, and repeating. After about 3 drinks I unlocked the achievement.
It's also easy to combine this achievement with Puking Rally. Just do this in an area with a lot of zombies and you'll pretty much get it automatically.