I just found out yesterday, that a woman I believe to be highly sensible and rational, totally believes in the evil eye. Once upon a time, she said, a guy asked her out and she said no, and he gave her the malocchio, which caused her to fall and sprain her ankle later that day. It, of course, had to be cured via that oil ritual thing that people do.
To quickly explain, the evil eye is when someone thinks bad thoughts about you (sometimes disguised by a compliment), and then bad shit happens to you. It is considered fact, not superstition, by many people in my family.
I sometimes suspect that it might be a thing that exists. It's kind of an odd thing because it's not like you always give it by announcing "I place the malook on you!" or whatever- it's not always conscious. You can give it by admiring something and being envious of it at the same time. Because of the color of my eyes, I'm supposed to be especially inclined to give people the malocchio. If it does exist and is something I do, I'm totally an asshole, because I can name like, 50 bad things that have happened to people after they've pissed me off significantly. But so can anyone, I would imagine, if they think hard enough on it- these things are just coincidences.
I also think that sometimes things of that nature are self-fulfilling prophecies. Once upon a time, back in NY, this one chick went and tried to put a curse on me. I found this out because my friend's aunt and uncle ran a Santerian store, and she happened to be there that day. Despite my rational nature, I gave second thoughts to every crappy thing that happened to me that week. I also used to believe that there was a curse on my birthday. I believed it so much that I'd end up freaking out over every little thing that happened on it and blaming it on the curse. It was pretty spooky though- one year a tree branch fell on my new car and totalled it. I think a Ramone died on my birthday as well. I also broke my foot one year. But it stopped when Reagan died on my birthday and I decided that that meant the curse was over. Nothing bad has happened since.
I don't really believe in these superstitions, but if I were you, I'd be nice to me.