Is Rachel in Costume or Is This Just Her Signature Look?

Rachel Bilson has always had an interesting sense of style, but when we saw The O.C. starlet heading to a friends house in hippie-ish bell bottoms, a headband and with peace, "love" and hearts written on her body in permanent marker, we couldn't tell if she's shed her 80's retro-style for a 60's era look, or if she's going as a hippie for Halloween!