John and Mary were having dinner in a certain city restaurant on Saturday night last and it was noticeable to other diners from their body language and the way they held hands that they had eyes only for each other. But, then, their waitress, taking another order at a table a few feet away, noticed that John was ever so slowly sliding down his chair and under the table. Mary, meanwhile, seemed unconcerned.

The waitress watched as John slid all the way down his chair until he was completely under the table and out of sight. All the while, Mary remained calm and unruffled, so much so that the waitress felt obliged to act.