Metamorphic Smiley

Yellow button with the image of a face that can either be smiling or frowning, depending on how the wearer places it. 

The classic yellow smiley face is comprised of a yellow circle, two black dots for eyes, and a black arc ending in serifs for a mouth. It was designed in 1963 by commercial artist, Harvey Ross Ball. Ball was commissioned by The State Mutual Life Insurance Company to create a happy face to raise the morale of their employees. His version was created in 10 minutes. The design was printed onto more than 50 million buttons. Neither Ball nor the company copyrighted this smiley, so it was continually used by other businesses in their promotions.
The design and concept is quite simple and was definitely used before Ball’s 1963 version. However, his has become the most iconic. Variations have been used for advertising campaigns and in popular culture ever since.

In internet culture the smiley face is often represented by a colon and a parentheses. :)

Metamorphic buttons are optical illusions formed when two images are drawn to look like one image. A reversible figure in a literal optical illusion requires the viewer’s perception to see one or the other image but both images are present. In this case, the button facing one direction creates the illusion of a happy smile with a wrinkled forehead from a smile or surprise. If the button is worn upside down, the smile is a from and the wrinkles look sad.