The song comes from The Big Bang Theory, where Penny sings it to Sheldon while he is ill, turning a simple childhood-style lullaby into a running joke about comfort and care. Fans kept quoting and singing it long after the show, and it later found a second life in short videos, especially clips of cats sleeping, being groomed or looking unimpressed. Its appeal is its instant recognition: a few soft notes tell viewers the moment is meant to be sweet, safe and a little absurd.