Twinkle Twinkle Little Star
From Tardis Wiki, the free Doctor Who reference
"Twinkle Twinkle Little Star" was a song that the Second Doctor played on his recorder after being plucked into the Third Doctor's timeline by the Time Lords. The Third Doctor was heavily aggravated with his predecessor's music. (TV: The Three Doctors)
The Eighth Doctor later did the same. (PROSE: The Taint)