The Rat Pack is the nickname given to a group of popular entertainers most active between the mid-1950s and mid-1960s. Its most famous line-up featured Frank Sinatra, Dean Martin, Sammy Davis Jr., Peter Lawford and Joey Bishop, who appeared together in films and on stage in the early 1960s. Despite its reputation as a masculine group of people, the Rat Pack did have female participants, such as movie icons Shirley MacLaine, Lauren Bacall, and Judy Garland. The name "Rat Pack" was first used to refer to a group of friends in Hollywood first informally organized around Humphrey Bogart, a group that included the young Frank Sinatra. The term "Rat Pack" was supposedly assigned to the original Bogart group by "Den Mother" Lauren Bacall, after seeing them return from a night in Las Vegas, she being the youngest of them all and seeing them to be tired and worn out said words to the effect of "You look like a goddamn rat pack", referring to the tired and haggard appearance of the other members of the group. According to another explanation, the term, "Rat Pack" was not Bacall's idea at all. It had started with Humphrey Bogart, Bacall's husband and frequent film co-star and a pal of Sinatra's, who named a group of his drinking buddies the Holmby Hills Rat Pack, after the location of one of Judy Garland and her husband Sid Luft's houses (a frequent hangout). Yet another explanation has it that the name referred to the way that an established pack of rats will belligerently reject an outsider who tries to join them.