Idiom of the day :- Say cheese

Usage, examples and definition of the Idiom :-

If you look into a mirror and say the word ‘cheese’, you will notice that you appear to be smiling. For that reason, photographers often ask you to say cheese when they are about to take your picture. ‘If you don’t mind, would you look into the lens of my camera and say cheese?’ Timothy asked. ‘And though you may look at my cheese and admire it, you may not have it. Just gaze at it, say cheese, and then I will return to eating it.’