From Polaroid’s FAQ:

Should I really “shake it like a Polaroid picture?”

Question:
Ever since the song “Hey Ya” by Andre 3000 of Outkast came out, everyone is shaking their Polaroid pictures. I have always been told that you should not shake a Polaroid picture, but I’m having a hard time convincing those around me that this is true. What is the answer?

Answer:
The short answer is no, you don’t have to (and shouldn’t) “shake it like a Polaroid picture.”

Shaking or waving a Polaroid picture to help the development process originated in the early days of peel-apart film. After peeling the negative, the image needed to dry before it could be handled, so waving the photo helped it to dry more quickly.

When using the integral films (600, Spectra, 500, SX-70/Time-Zero, i-Zone) that are used in our most popular current camera models (Polaroid One, OneStep, JoyCam, etc.), the image develops and dries behind a clear plastic window and never touches the air, so shaking or waving has no effect.

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.

The best way to ensure a perfectly developed image is to simply lay the picture on a flat surface immediately after it exits the camera. Shield it from the wind and avoid bending, twisting, or otherwise disturbing it during development.

Polaroid FAQ