My fear of things is directly related to the number of legs that they have. Snakes? Aww. Humans? I guess they could stab me if they wanted to. Cats? Those suckers have claws. Ants? Eh, keep it over there. Spiders? HOLY SHIT KEEP IT AWAY! Centipedes and above? I'm glad I live in a country where those are really uncommon.
I also have a really terrible fear about heights when it's something I can't control. Like, if I'm the one on the heights, I'm fine. But one time a friend leaned against a stairwell banister at school and I began to have vivid ideas of the thing breaking and him falling. I knew I would be smart enough to avoid it, but I wasn't so sure about him. I had to leave to avoid the embarrassment of saying something.