Shack Up Meaning

(idiomatic, pejorative) To live together, especially of an unmarried couple.

Example:   I don't think his father was too thrilled when he shacked up with his girlfriend.
  1995: "George, please state the name of the hotel and room number you are in."
"Room 832 of the University Plaza Hotel."
"Lynn, please state the name of the hotel and room number you are in."
"Room 832 of the University Plaza Hotel."
Dr. Daniels interrupted. "Christ, Hugo, are you trying to tell me you've got these two kids shacked up in a hotel room?", In The Matter of: The Gatekeeper: The Gate Contracts, Paul Robinson