You cannot forget about white contact lenses while going out for a Halloween party or a Zombie Walk. White contacts give you the creepiest look ever! The ones that cover the whole eyes (including the pupil) give the observer the impression that you have no eyes and there's no way of determining where you are looking, which is very disturbing. So don't let anybody have a better costume - buy white contact lenses and be the scariest character at the party!
Image by Making Hell