A trustfunder who pretends he/she is poor by taking on what he/she perceives as downmarket accoutrements, lingo, etc. Goes beyond "slumming it," as the appearance/manner/speech matches the environment in which the "slumming" plays out. In extreme cases, may manifest itself as a street musician playing for change, a runaway sleeping in doorways, or Muffy the stripper.
Usually a phase in which apathetic and/or nihilistic rich kids indulge themselves until Daddy or Mummy snaps them out of it with a threat to disinherit/cut off funds.
She's more like from Bedford Hills than BedStuy. The girl's a fauxbo!