Hexing Someone Options

So i was wondering about hexing someone i was reading Anton Szandor LaVey's Satanic Bible and there is a passage in there that describes hexing someone. And from what i got from it (Just my own interpretation of it). Was that when hexing someone that they have to know of it even if they dont believe in magick or anything just the fact they know your putting a hex on them can trip them up and cause problems. But i was curious what if you did'nt tell the person that you were hexing them and they had no clue about it would it still have an effect on them? What are your ideas on this? This caught my attention i figured if you curse them without them knowing that the effect would be the same am i right to assume this?

Ha thank you bym very insightful. the bullet metaphor actually helped out quite a bit (IMG:style_emoticons/default/smile.gif). Yes i was just curious on this it was confusing to me i just needed some insightful information on it appreciate the post.