Warm Kitty

"Warm Kitty" is a children's song, popularized by the characters Sheldon and Penny in the American sitcom The Big Bang Theory where it is rendered as "Soft Kitty". According to claims in a copyright lawsuit, the words to "Warm Kitty" were written by Edith Newlin. The original version is a very popular Polish traditional lullaby "Wlazł kotek na płotek", a folk tune from the 18th century.

In The Big Bang Theory the song is described by Sheldon as a song sung by his mother when he is ill. The lyrics on the Big Bang Theory are: "soft kitty, warm kitty, little ball of fur! Happy kitty, sleepy kitty, purr purr purr!"

Versions of the song have been released by Australian children's performer Patsy Biscoe, and by the long-running ABC children's programme Play School which predates Big Bang Theory and has the lyrics reversed, instead going: "Warm kitty, soft kitty, little ball of fur. Sleepy kitty, happy kitty, purr purr purr." The song remains part of Play School's catalogue of children’s songs regularly performed on the program: the show's presenters occasionally perform the song for their young viewers.

By Christmas 2011, "Soft Kitty" merchandise—such as a plush stuffed singing cat, or T-shirt with the The Big Bang Theory version of the lyrics—could be purchased.

In December 2015, the heirs of Edith Newlin filed a lawsuit against the various companies associated with The Big Bang Theory, claiming that the words and music to the song appeared in the book Songs for the Nursery School published in 1937 by Willis Music, based on a poem by Newlin; the copyright to the book was renewed in 1964. The website for Willis Music states:

"In 1937 we published a book called Songs for the Nursery School and we sold tens of thousands of copies. It is a hardbound book of over 150 songs for children. The book was written by Laura Pendleton MacCarteney. In that book on page 27 is 'Warm Kitty'.... Warner Brothers and I worked together to secure the rights for the show The Big Bang Theory and they have been using the song ever since."

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