back alley bitch
A woman with an appetite for sordid sex on the sneak, especially with strangers, and who frequents establishments where she can meet them and let them get her out into the "back alley." She often gets a particular thrill from going down on her knees and performing oral sex in the litter-strewn street.
One of Mike's friends saw his wife leaving a bar by the back door with another man, and the word soon spread to everyone but Mike that Bonnie was a dirty little back alley bitch.