Mischa Barton participated in the time-honored celeb holiday ritual of stripping down to her itty bitty bikini and warming herself somewhere tropical. The celebrity body runs 4 degrees cooler than us regular folk, which is why they must venture towards warmer locales in the chilly months. It’s not a mere vacation: they have to do it to stay alive.

We caught up with the former O.C. actress as she was sunning herself on the beach in Miami this morning. Gotta love the tiny bikini, huh? Mischa was with a cute male friend – a new beau, perhaps?

Mischa seemed to be a little self-conscious – when she noticed photographers, she tried to cover herself up a bit.