Re: Straight Dope Staff Report: Why do photographers ask you to say “cheese”?
20-Sep-2005 http://www.straightdope.com/mailbag/msaycheese.html
My father was a professional photographer for a number of years, and found that “cheese” resulted in kids and adults jutting out their jaws and delivering a cheshire cat grin.
His invariably more sucessful suggestion was “cat sht!" Try it … saying “cat” forces one to open one’s mouth and separate the lips to expose the teeth, and the "sht” part forces a flattering lifting of the jaw as one produces the “sh” part.
Needless to say, the baseline naughtiness involved usually lights up kids’ eyes and tended to give an unrehersed (wicked) smile