In Sam's unfortunate presence (unfortunate for Sam in more ways than one), Anthony and Annie tell Carla and Eddie that they're expecting - meaning Carla will become a grandmother - and that they plan on continuing to live at her house after the arrival of the baby. Carla is angry and goes into a deep depression. Carla implies that her issue is that she has gone from being a child herself to being a grandmother, missing out on her own growing up, including her adolescence and middle age. Being a grandmother means her life is almost over. This news in turn affects Rebecca as Carla is in hibernation while she awaits "the angel of death", so Rebecca is short staffed at the bar. Rebecca, who herself has to schlep drinks to the customers, is a reluctant and lousy waitress. The gang think that something that Carla referred to - a slumber party - might get her out of her funk, as in the words of Lilith, recreating a childhood ritual often helps in getting one out of depression around aging. However, all the slumber party invitees - Rebecca, Lilith and Lilith's childhood friend Dorothy - are all unfamiliar with the rituals of slumber partying, which results in an atypical gathering. However, an unwitting act by Cliff may finally gets Carla out of her depression.
—Huggo