Disgust of looking at veins.
When I look at them, I think that someone's going to inject drugs into them then rip them out then play 'Fur Elise' with them, honestly, this is not a joke. I dare turn my hand around, I close my eyes in a fierce manor until it hurts.
In fact, I don't even touch them, I only touch them twelve time's a year they scare me that much, even so, I put my hands in my pockets so I can't see them.