Thanks to Seth Godin for comments & link to this CNN story:
Have you ever noticed that whenever people take a Polaroid picture (even professionals), they shake the film a little bit before they peel it?
In fact, I've never seen anyone NOT shake it.
Where did shaking start? How did we learn to shake? How does one person learn about shaking--from someone else?
Anyway, all that was answered today: CNN.com - Polaroid warns buyers not to 'Shake It' - Feb. 17, 2004