AUDIO Cameo Appearances

Recently there was a topic here about cameos by musicians in movies, but what about Audio cameos? Do you have a favorite? It could be a fun example like the one I'm posting here, or it could be a duet - credited or not - by another performer. Which ones stand out to you?

http://www.youtube.com/watch?v=ot70G4wSQi0

Lloyd/Goldtop/Queen of Clubs

Here's another one I like myself. Also Canadian...

http://www.youtube.com/watch?v=Jx6_-urg5fo

Goldtop

Gotta go with "Angel Mysterioso" (IIRC) which was George Harrison helping EC on "Badge".

Gotta like EC's uncredited work on "While my Guitar Gently Weeps" also.

Wendy O. Williams featuring Ace Frehley - "Bump And Grind":

http://www.youtube.com/watch?v=J0LdKpPnwEY

Warren Zevon with Billy Bob Thorton, Tommy Shaw, John Waite and more - "Knockin' On Heaven's Door":

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

God I miss Warren. That same album featured Springsteen on "Disorder In The House".