NEW YORK -- One recent evening, I celebrated my birthday in the outdoor courtyard of a bar. As the night wore on, and friends fell by the wayside, each departure occasioned a small ritual. A pal would sidle up to whichever conversational circle I was in; edge closer and closer, so as to make herself increasingly conspicuous; and finally smile, apologetically, when the conversation halted so I could turn to her and say goodbye.Nothing but good intentions here. To some small extent, I appreciated the politeness of this parting gesture. It was not a major imposition to pause for a moment and thank folks for coming.But there's a better way. One that saves time and agita, acknowledges clear-eyed realities, and keeps the social machine humming.Just ghost.