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2.
To do that which is both unnecessary and uncalled for, for the purposes of self-amusement. Always has a victim, often oneself.

In order for something to be a genuine Castaldo, the thought process behind it must be made immediately before the act, but in a form of retroactive hypothesis. The idea is that before you perform a Castaldo, you think about how amusing it will be in retrospect, as opposed to how irresponsible and dangerous it is in the immediate future.

Origin; Italian-American - New Jersey.
"Yes, I'm leaving you with my car keys. Don't Castaldo like last time: It took forever to dig that hooker's fingernails out of the grill."
by CliveChurchMusic May 23, 2010
 
1.
Verb. To do that which is both unnecessary and uncalled for, for the purpose of self-amusement. Always has a victim, often oneself.
Head-butting that guy on a whim was definitely Castaldoing.
by Bruce Thomas April 04, 2010