Watching a TV tennis match, a kid swears in front of his parents for the first time. — I’m in the den with Dad, watching McEnroe versus Borg. The tennis ball makes a fat popping when hit. I’m all for Borg because he’s quiet, patient, seasoned and wise, hanging along that baseline, waiting for McEnroe to come in. McEnroe is younger, brash, ballsy. He hunts the ball, smacks…