Once when you take down a zombie, dont just walk away, also double tap that demon, dead, ugly thing. If you dont do this then the zombie will just get right back up. Now being that zombies are dum and stuff, they wont know when to stop besides, they would eat cow **** if it had meat in it, so right there, that prooves they have no brain, so they come after you because you have one or something like that, I dont know, just ask Abraham Lincoln for christ sakes..... But anyways, zombies need double tap in their head. Now just because zombies are dum, doesnt mean underarrestamate them because the second you do...well um lets just say, you wont be sticking around much longer.