Honestly, I don't really have many phobias. I'm not really scared of much. I chalk it up to denial and an irrational belief in my own invincibility.
If I had to pick something, I guess it would be having my hand crippled or amputated. I can't imagine living without them. Or, more accurately, I can and the thought of it sucks. And the worst part is, it becomes super hard to properly kill yourself without hands, so even if you were suicidal you couldn't do anything about it.
Oh, and I can't stand gross toenails and feet. I work in a hospital so I have to touch them and work with them all the time. Always sucks.