shack up
phrasal verb with shack verb uk/ʃæk/ us/ʃæk/
informal
（未婚）同居
to start living in the same house as sexual partners, without being married
I hear Tony and Helen have shacked up together. 我听说托尼和海伦已经同居了。
She is shacking up with her boyfriend. 她决定和男友同居。