"Warm Kitty" ‘TBBT’: Sheldon Cooper Lullaby Infringing Copyright, Lawsuit Claims Song’s Stolen

Some of the best scenes in The Big Bang Theory have been about how Sheldon Cooper (Jim Parsons) and Penny (Kaley Cuoco) sing "Warm Kitty" to each other, and though the song was believed to be originally made for the show, a new lawsuit shows the heirs of poet Edith Newlin think otherwise.

According to USA Today, a family recently filed a lawsuit against the show's producers, CBS and other media companies associated with the two, saying they've been violating copyright for a song/poem about a "soft kitty" that Newlin wrote in 1937; the heirs claim they've never seen a dime from TBBT's use of the material.

Newlin's two daughters, Ellen Newlin Chase and Margaret Chase Perry, claim that the show uses lyrics a little too similar to the 78-year-old poem and they've never paid for the rights, despite how popular the award-winning show has been over the years.

Newlin's heirs claim that the original song has been used in its entirety on at least eight episodes of the long-running show, which is currently in its ninth season.

It appears as though the show's producers sought permission to use Newlin's lyrics in 2007, contacting Willis Music Co., the company that published the poem in the book Songs for the Nursery School, which in turn approved the use without ever contacting Newlin's family, even though the book's acknowledgement page makes it clear that Newlin owned copyright to the lyrics.

"The Soft Kitty Lyrics are among the best-known and most popular aspects of The Big Bang Theory," reads the lawsuit, via Associated Press. "They have become a signature and emblematic feature of the show and a central part of the show's promotion."

In fact, there's a lot of TBBT merchandise referencing the song, which has become a staple of the show. Actually, the stars have even sang it during Comic-Con appearances.

Newlin's daughters are currently seeking an unspecified amount from Warner Bros. The company hasn't stepped forward to speak about the lawsuit yet.