Yoko Ono has a lead vocal on what Beatles' song?

Short, but clear, she sings the solo line "not when he look so fierce" on Bungalow Bill, as well as joining in on the the chorus.

http://www.answerbag.com/q_view/489402

And here's a clip of her jamming with the Beatles in an outtake from Let It Be. There don't appear to be any clear lyrics, though!

http://www.youtube.com/watch?v=SYqCpvzXGTE

Revolution -- Unreleased versions of the song, including demos and outtakes, can be found on many bootleg albums such as "From Kinfauns to Chaos" and "Revolution", on which appears a twenty-three minute version of the song with Yoko Ono taking over vocals.

https://en.wikipedia.org/wiki/Revolution_(song)

From the 1968 self titled album 'The Beatles', commonly known as 'The White Album' by its fans, 'Birthday' side three song 1, or side two song 1, or track 18 *lol*. In the Chorus

"I would like you to dance (Birthday)
Take a cha-cha-cha-chance (Birthday)
I would like you to dance (Birthday)
Dance"

The word BIRTHDAY is sung by Yoko Ono

http://www.youtube.com/watch?v=hMb1wPfE1Iw