What is soft kitty warm kitty?

"Soft Kitty Warm Kitty" is a children's nursery rhyme that became popular through its appearance in the television show "The Big Bang Theory." The song is typically sung to a soothing melody and describes a cat that is soft and warm. It is often used to provide comfort or to help someone feel better when they are feeling sick or sad. The lyrics of the song are repetitive and simple, making it easy to remember and sing. The calming and reassuring nature of the song has made it a popular choice for lulling children to sleep or providing a sense of comfort in stressful situations.