The Metropolitan Museum of Art's Costume Institute Gala may be one of the biggest society events of the year, but it's also a time for the fashion cognoscenti to be a bit playful -- they are among friends after all.

Here's a look at some of the cheekier outfits of the night, and a guess at who may have played muse to these style mavens:

Model du jour, Agness Deyn, inspired by blonde bombshell Marilyn Monroe. Photos by Getty Images

It girl, Anne Hathaway, inspired by the original "That Girl," Marlo Thomas. Photos by Getty Images

Très fab, tuxedo-clad Rihanna, inspired by penguins. Photos by Getty Images