"Baa, Baa, Black Sheep"
From Tardis Wiki, the free Doctor Who reference
"Baa, Baa, Black Sheep" was a song with a simple melody.
The Second Doctor played it on his recorder. (AUDIO: The Great Space Elevator)
Behind the scenes
In the comic story The Weeping Angels of Mons John McHugh voices his displeasure by saying "three bags full, sir", which is a line from this song.
