Las Brujas y el Cura is a Galician (which is an autonomous region of Spain) folktale. I first discovered it in my Spanish class, we read a version of the story in Spanish as part of learning the differences between the preterite and imperfect tenses. The title is literally translated as The Witches and the Priest. It tells of a young, clever priest that is transfered to a small-town parish. He quickly befriends the children of the village, playing with them and telling them stories (and no, nothing untoward was happening between the children and the priest). In fact, they love him so much that many of them end up going to Mass every day.
One day, the children bring up the subject of witches, or brujas in Spanish. They don't believe that the priest can distinguish between the women of the village and the witches. The priest rises to the challenge and brashly tells the children to wait and see what happens after Mass on Sunday.
Sure enough, after Sunday Mass, the young priest, after dismissing the congregation, doesn't close his Bible. As the people are filing out, several women stay behind in their seats. After the rest of the flock leaves, the women scream at the priest to close his Bible; they are the witches of the village and cannot leave the church with the Bible open for some magical reason. However, the priest refuses to close the Bible. At this point, things start getting hairy; the witches threaten to curse him if he doesn't close the book. Finally, the priest relents, closes the Bible, and the witches run out. Unfortunately for the priest, the story doesn't end here, the witches are upset at his impudence and proceed to torment him. In the end, he requests another transfer and is never seen from again.
The morals of this story: never become so overconfident in your abilities that you rush headfirst into danger and never do anything just on the basis of a dare, impressing people isn't important.
note: If you want to read more Galician folktales, see La Manzana del Enamorado and Lo que le Pasó a un Hermano Mio. If you want to read Mexican folklore see El Virrey y el Azteca.