1. Makeup. A type of powder-based foundation named for the flat round container in which it comes. Or, because it was a "cake" of talcum powder, pigments, and oil, shaped in a shallow pan for ease of application.
From http://www.cosmeticsandskin.com/bcb/cake.php :
Invented by Hollywood make-up artist Max Factor as an alternative to greasepaint, which worked fine for B&W films but was too heavy for color. Pancake make-up debuted in the color film Vogues of 1938. Pan-Cake™ is still a trademark of Max Factor.
How to Apply Pancake Makeup | eHow.com
2. Film/TV. Nickname for a 1" thick, Eighth Apple Box.