Now that many have heard Outkast's line "shake it like a Polaroid picture" in the song "Hey Ya," Polaroid is trying to get people to know that shaking may be bad for the pictures. In older Polaroid cameras, people shook them to dry photos quicker.

Polaroid points out that this is no longer necessary since the photo dries behind a clear screen while the developing picture "never touches air, so shaking or waving has no effect." Polaroid has noticed many still shake the pictures.

Polaroid warns: "In fact, shaking or waving can actually damage the image. Rapid movement during development can cause portions of the film to separate prematurely, or can cause 'blobs' in the picture."

Source