Soft Kitty

Soft KittySoft Kitty is a song that Sheldon's mother used to sing to him when he was sick. The song, which features altered lyrics written by co-creator and executive producer Bill Prady, is based on an Australian children's song, "Warm Kitty", written by Edith Newlin. The original song's melody is identical to a German song, "Hanschen klein".

The lyrics for The Big Bang Theory's version are: Soft Kitty, Warm Kitty, Little Ball of Fur. Happy Kitty, Sleepy Kitty, Purr Purr Purr.

The song was first introduced in the Season 1 episode The Pancake Batter Anomaly, where a sick Sheldon asks Penny to sing the song to him. The song's latest mention was in the Season 8 episode The Anxiety Optimization where Leonard and Penny sang the song to Sheldon to get him to fall asleep.

A line of officially licensed t-shirts nad merchandise has been released, some of which feature the song's lyrics.

Featured in these episodes:

  • Season 1, Episode 11 - The Pancake Batter Anomaly

    This episode features the first mention of Soft Kitty. When Leonard, Howard and Raj abandon Sheldon after he catches a cold ("code milky green"), Penny is left to take care of him. Sheldon asks her to sing him Soft Kitty, as his mother used to when he was sick, and so he teachers Penny the words.

  • Season 2, Episode 21 - The Vegas Renormalization

    After Sheldon is locked out of his apartment and forced to the spend the night at Penny's, he asks her to sing Soft Kitty to him. Penny says that's only for when he's sick, but Sheldon points out that homesick is a type of sick, so Penny relents and sings the song.

  • Season 3, Episode 8 - The Adhesive Duck Deficiency

    The roles are reserved in this episode as Sheldon must take care of an injured Penny. Following a trip to the hospital, a medicated Penny asks Sheldon to sing Soft Kitty to her. Sheldon initially refuses as Penny isn't sick, but she counters that injured and drugged is a kind of sick. After Sheldon relents and starts singing the song, Penny suggests they sing it as a round.

  • Season 4, Episode 2 - The Cruciferous Vegetable Amplification

    After Sheldon injures himself running down the stairs with his vintage 1977 Apple Two, Sheldon sends his virtual presence device, which Penny nicknames Shel-Bot, over to her apartment. He asks her to sing Soft Kitty to the computer monitor. When Penny starts singing, Sheldon begins to play the tune on the recorder.

  • Season 5, Episode 6 - The Rhinitis Revelation

    After Sheldon catches a cold, Mary sings Soft Kitty to him as she applies VapoRub to his chest and puts him to bed.

  • Season 5, Episode 18 - The Werewolf Transformation

    As Penny tries to convince Sheldon to let her cut his hair, she points out all the things she does for him, including singing Soft Kitty.

  • Season 6, Episode 22 - The Proton Resurgence

    In a hospital room following his health scare, Sheldon sings Soft Kitty to Professor Proton. When Sheldon offers to sing it for him again, Arthur tells him the fourth time was the charm.

  • Season 8, Episode 13 - The Anxiety Optimization

    After Sheldon drives himself crazy by staying up for days on end, Leonard and Penny try to put him to bed. When Sheldon tells them they can't make him go to sleep, Leonard and Penny sing Soft Kitty to him, at which point he falls right asleep.