Originally Posted by fastball

Jeremy Spencer sound check with Fleetwood Mac on an old upright outta tune piano singing Blood on the floor.
Heroin in a club with about 75 people and Lou Reed and the Velvet Underground.
The End with a little known band called the Doors with about 50 people.
She Loves You by the Beatles two rows back with thousands of people.

Forgot one great one....Louie Louie with Frank Zappa and the Mothers of Invention.