There was the following sentence in the New York Times (April 5) article titled, “Steak for Two, Please, With a Side of Bribes” dealing with a recent bribery case of a New York State Congressman and a City Councilman. http://www.nytimes.com/2013/04/06/nyregion/steak-for-two-please-with-a-side-of-bribes.html?nl=nyregion&emc=edit_ur_20130405&_r=0
“The link between corrupt politicians and steakhouses would appear to be so obvious that corrupt politicians would avoid them altogether, especially since there are apparently as many hidden microphones as shrimp cocktails at a given table. But still they come. Experts on either side of the napkin offered theories. “They’re men,” said Ben Benson, the owner of a steakhouse. “Men go to steakhouses. The power lunches, the power dinners — it’s what the steakhouse is all about.””
Though it seems ‘Expert on either side of the napkin” simply implies restaurant business expert to me, what does it exactly mean?
Does the word, “napkin” have any specific metaphoric or symbolic meaning other than “a small square piece of cloth or paper, used while you are eating to protect your clothes or to clean your mouth or fingers” defined by Cambridge English Dictionary? Is “Expert on the napkin” a word on everybody’s lips?