A young lady of easy virtue who is usually, but not always, aesthetically and hygienically challenged. Usually predominant in packs of Chavs or Neds. The literal definition refers to the female genitalia in a constant state of readiness as in, '....hanging out'.
I wouldnae go near her, she's a fuckin' hing oot.
I think ah caught somethin' fae that wee hing oot last night.
The most popular use of this term, however, is a form of male bonding and acceptance: Yer maw's a fuckin' hing oot.