you have reached a step one, first you must launch a game of standard (any map)

when you are in a game, there are the zombies with their arms out, run from them! Very important step here. (dont worry, they just trying to give you a hug to make you less scared of the dark)

when there is a fat zombie that is leaking green, give him some sleeping pills (your pistol fires these) and the zombie will explode with releif because he has not slept in a long time

when the zombie explode, make sure your in the red circle, as the green stuff will kill you because farts are deadly :(

you say a thank u as the zombie this will give you the Terrible night to have a curse acheivement
I hope this guide help you