Great, unexpected, live musical collaborations

I went down a YouTube rabbit hole tonight. Along the way I came across this phenomenal (IMO) and unexpected version of “Because The Night” by Bruce Springsteen and Michael Stipe.

What unusual live co-appearances have you enjoyed?

Robert Downey Jr and Sting - Driven to Tears - Robert Downey Jr Sings With Sting - YouTube

That’s a great example. (Although I can’t help thinking RDJ was mimicking Sting…) Still, shockingly good!