shackswitch 

Verb. (1) to compel someone who is currently in a relationship to date you instead (2) to change your dating partner

Noun. (2) an external compulsion to switch one's current dating partner that may or may not be brought on by a shackwrecker. (3) the act itself

Other forms...shackswitching, shackswitched

Although Joanna was dating Craig at the time, Joseph convinced her to make a shackswitch.

shackswitch by Ambina D'Bidanza May 9, 2011

Smackwitch 

A female heroine addict, especially one that shows years of drug abuse in her appearance and behavior. She is missing many teeth, and the ones left are rotten as all hell. See also Crankwitch and Crackwitch.

Fucking smackwitch whore squatted and pissed right next to the minivan, with me and the kids sitting right there! Welcome to San Francisco kids.

Smackwitch by Jim Inman August 20, 2006