John and Mary were having dinner in a very fine restaurant. Their waitress, taking another order at a table a few paces away, noticed that John was ever so slowly sliding down his chair under the table while Mary acted unconcerned.
Their waitress watched as John slid all the way down his chair and out of sight under the table. Still, Mary appeared calm and unruffled, apparently unaware that John had disappeared under the table.
After the waitress finished taking the order, she came over to the table and said to the woman,
"Pardon me, ma'am, but I think your husband just slid under the table."
The woman calmly looked up and replied firmly, "Oh, no. He did not. In fact, he just walked in the front door."