swinger/swinging single
形容一個喜歡放浪不羈,自由生活的人

explanation: Popular slang in the 1960s.  A "swinger" was someone who enjoyed a wild lifestyle, and went to lots of parties.  You'll see this word in many movies and books about the 60s. 

e.g. Paul's out late again, hitting the party scene.  He's such a swinger.