The evil eye is the name for a sickness transmitted -- usually without intention -- by someone who is envious, jealous, or covetous. It is also called the invidious eye and the envious eye. In Hebrew it is ayin ha'ra (the evil eye), which in Yiddish is variously spelled ayin horoh, ayin hora, or ayen hara. In mainland Italian it is mal occhio (the bad eye) and in Spanish mal ojo or el ojo (the bad eye or just the eye). In Sicily it is jettatore (the projection [from the eye]) and in Farsi it is bla band (the eye of evil).

Dundes theorizes that the evil eye, which has a Middle-Eastern, Mediterranean, and Indo-European distribution pattern and was unknown in the Americas, Pacific Islands, Asia, Sub-Saharan Africa or Australia until the introduction of European culture, is based upon underlying beliefs about water equating to life and dryness equating to death. He posits that the true "evil" done by the evil eye is that it causes living beings to "dry up" -- notably babies, milking animals, young fruit trees, and nursing mothers. The harm caused by overlooking consists of sudden vomiting or diarrhoea in children, drying up of milk in nursing mothers or livestock, withering of fruit on orchard trees, and loss of potency in men. In short, the envious eye "dries up liquids," according to Professor Alan Dundes -- a fact that he contends demonstrates its Middle Eastern desert origins.
Only in Sicily and Southern Italy is it believed that some people can DELIBERATELY cast the evil eye on others. There the regionally idiosyncratic belief is that certain people (including at least one former Pope) are born with the evil eye and "project" it involuntarily. Such people are called jettatores ("projectors") and their specific form of evil eye is called jettatura ("projection") in contradistinction to the garden variety of envious or praising evil eye, which in Italian is called mal occhio ("bad eye"). Jettatores are not necessarily evil or envious people, according to this belief system, and they are often represented as being saddened and embarrassed by the harm they cause.
In the eastern Mediterranean and Aegean region, especially throughout Greece and up into Turkey, there is a strong tendency to view blue-eyed people as bearers of the evil eye -- probably because few locally-born people have blue eyes and those who do show up, such as tourists, are given to praising and cooing over babies, who are thought to be most at risk from the eye.
In Italy, the evil eye is said to affect men as well as children, nursing mothers, fruit trees, and dairy animals. It brings on impotence, through a drying up of the semen. Typical protective aversions of this problem include making the gestures called the mano fico ("fig hand") and the mano cornuto ("horned hand").
Mano fico is a hand gesture in which the thumb is inserted between the index and middle finger. It means literally means "fig hand" in Italian, but "fica" or fig is a common slang term for the female genitals, so the mano fico is a representation of the sex act (with the thumb as phallus).

All so very interesting. Watch out-- I'm dangerous one look and Bla-band! And I will not spit on you!