The Sicilians are very superstitious people, almost more than being devout Roman Catholics:
When entering someone's home, always leave through the same door you can in from, otherwise its bad luck
Never put a new pair of shoes on the kitchen table
Put brand new shiny coins on the window sill before midnight on New Year's Eve for good luck, place them heads up!
Bury a mini plastic statuette of St. Joseph upside down on the front lawn if you want your house to sell
Never give pearls as a present, they are to be inherited only
The 'horns' is kind of similar to "I'm rubber, you're glue, whatever you say bounces off me and sticks to you", so if you wish someone harm who wears this pagan jewelry symbol, it will return to you to haunt you
When in dire need of prayers for the sick, dead or dying, go to church and light a candle

Required Reading for Italian-Americans...