To excommunicate someone is to throw them out of the Catholic Church. Generally, only the Pope can excommunicate people, but there is a rumor that Chuck Norris has excommunicated someone before. Not to be confused with Ex-Communicating, which is generally frowned upon, unless you get yourself some sweet booty. Which is unlikely, seeing as the person in question is your Ex to begin with. Note: Excommunicated Catholic girls are always, always horny. This is a good thing.