I was surprised that so many do believe in jinx, me I think it's all just silly superstition. One that I grew up with is that if you where with a few people and two of you said the same thing, at the same time, it was jinxed, you where to say "jinx, one two three you owe me a coke" another was that if you stepped on a crack you broke your mothers back, and line and your dad's spine. There are several myths in baseball, Im not a bit sports orientated so I dont know, and it does not surprise me
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Through out history there has been historical "things" said to be jinxed, The Hope Diamond, any one who has owned it has suffered tragic deaths. Marie Antoinette did not have a very happy ending.
One thing I do know for sure is that mind is a very powerful tool, and if it's done correctly (I do not advice it) I am very sure you can jinx someone or somethings. Jinx is to give someone a case of the "bad lucks" or a curse on something like the hope diamond can cause bad things to happen. I think there was a curse on a broom in Harry Potter, lol I never did follow those stories so I dont know about that one either.
Recently I ran across a spell that I know would work, I commented on it by saying that I think I would have to add that I would want no curse returned, and to harm none. It was calling upon Hecate to see that justice is done to someone that has hurt another. As I said it would have worked, would I do it? It would have to be under extreme circumstances, and very carefully worded. I've had things come back to bite me magically and though it's never been something really bad, it was a price I paid. I say careful for what you ask for, Stand back and let Karma do her job, do not get in the way of Goddess's work. Merry magical workings, and blessed be.