A person who, upon arriving at college, adopts the look of the counterculture, including, but not limited to wearing their hair in dreads, listening to the Grateful Dead, and smelling like patchouli - until their parents come into town, or they are offered a job, or get busted for weed, after which they revert to the preppy look they had in high school.
You should've hooked up with that hot hippy chick last night!
That girl? She's just a pseudo-hippy. I'll wait until she washes her hair after Parent's Weekend.