A Jittery Nutcase made the scene this morning at Our Favorite Starbucks, intent on scaring-up a cup of coffee and scaring away the customers. "Hey, man," he said to me, "Buy me a cup of coffee, wouldya?" "No, thank you," I replied, retreating into my newspaper like a turtle in a shell. The next thing I knew, he went into "Nutcase Overdrive," running into the Parking Lot and threatening a Serious Athlete who was wearing a "Boxing Hall of Fame" T-Shirt. "I don't care if you have a mustache," yelled the Nutcase, inexplicably, "I'll do what I damned well please." For the record, the Athlete -- a man named "Castle" who doesn't have a mustache -- simply nudged the Nutcase aside and shrugged the incident off. "That was nothing," said Castle, "Last week he called me a Little Old Lady ...!"