Check out this clip from "Give My Regards to Broad Street" featuring Sir Paul McCartney.

 

To film this scene, McCartney did a legitimate street performance, with people walking by without knowing it was really him.

Here are some quotes from Paul about the scene:

"Y'know, they just made me up and dropped me off. I told 'em we'd never get away with it, but they kept putting dirt on and rufflin' up me hair -- I was looking better and better -- and I figured, why not.

So I was standin' there plunkin' chords, doing this silly version of the song, and no one noticed it was me. No one wants to look a busker in the eye of course, 'cus then they'd get his life story. So they'd toss coins and I'd be going, 'Yesterday, all my troubles -- thank you, sir -- seemed so far away.'

This fabulous drunk Scotsman, who didn't know me from Jesus, came up, threw his arm around me and gave me all his coins. I started doing these little dances and some punks came by, studs and leather, and they were dancing, too. Not because this guy's a Beatle, but because this was something happening.

It was a great feeling. Just me and the music."