Soft Kitty was a song created by Chuck Lorre for the Big Bang Theory as a comforting lullabye for Sheldon Cooper, one of the main protagonists/antagonists of the show. Whenever Sheldon feels ill, he asks Penny or his mother to sing it to him.
On occassion, Sheldon has sang Soft Kitty to comfort Penny when she needed comforting.
The song goes:
Soft Kitty, Warm Kitty
Little Ball of Fur
Happy Kitty, Sleepy Kitty
Purr Purr Purr.
This song is a good lullabye for anyone really, heck, it has a nice melody, it's about kittens, which most people love, and it is soothing. So next time you need some soft lulling into dreamland or a soft song to comfort you, Soft Kitty is a good song to choose.