When we saw the Huffington Post entertainment headline "TEETH! Mary Kate Olsen As You've Almost Never Seen Her", we could barely believe it. Did Ashley's tiny twin, er, sister, er, womb-sharer actually brave the New York air and open her mouth? Did she muster up the confidence to smile in a way that didn't involve sucking in her cheeks? We clicked through to see, and it was true! At the Cinema Society premiere of her film The Wackness, WireImage captured the rarest of Olsen poses: the genuine smile. And … it's … lovely! Good for you, M-K! We dig it!

Just don't smile too much. That releases endorphins, and those can become addictive. Next thing you know, you'll be exercising.

"TEETH! Mary Kate Olsen As You've Almost Never Seen Her" [HuffPo]

Related: Olivia Thirlby Spurns Pot, Embraces the Munchies [NYM]