Killing Zombies

I was in line at Subway today behind this guy in desert camo and a pistol on his hip. He was a cop, I guess? Anyway his T-shirt said "Some people kill zombies and some people feed them, which one do you want to be?" First thought was: that's way too much text for a T-shirt. Second: WTF does it mean? I'm assuming it's referring to a zombie apocalypse and how he'd be ok because he had a gun. Or he has a zero tolerance policy for people on bath salts.  Really I don't know. Utah is weird.