In the area where I live, silly is a synonym for ZURULLO ( that is a piece of shit ) because the word ZOCATO ( left-handed ) You can derive from silly, because there is a custom in other cultures to clean the anus with the left hand ( left-handed or zocata ).Is a very common expression in my land, when one is very frightened or is " shit " of fear, we say: " is the silly ass "