I Don't Want to Set the World on Fire

While performing maintenance on his TARDIS, the Third Doctor sang a song containing the lyric "I don't want to set the world on fire". Ironically, smoke erupted from the TARDIS shortly afterward. (TV: Terror of the Autons)

Behind the scenes
The Third Doctor sings the titular line of I Don't Want to Set the World on Fire in the episode Terror of the Autons. However, the title is not explicitly stated on-screen. Though the song has been recorded by several musicians and groups, the one the Doctor is singing is the The Ink Spots' version from 1941.