"Singin' in the Rain" is a song with lyrics by Arthur Freed and music by Nacio Herb Brown. The musical film of the same name, Singin' in the Rain (1952), was "suggested by" the song. The performance by Gene Kelly dancing through puddles in a rainstorm garnered the song the third spot on the American Film Institute ranking of 100 Years...100 Songs.
Thanks to Bob Saunders for the inspiration!