Carrie Underwood had a fun weekend! The Rolling Stones performed in Toronto Saturday night and she was there...on stage with Mick!

The Stones were performing "It's Only Rock and Roll" then Carrie comes on stage and sings side by side with Mick. How Cool! She thought it was pretty cool too because she tweeted afterwards:

I just sang with the ! Holy cow! I walked off stage and said, "What just happened?!" Still can't believe it! :)

Catch the performance below. Carrie comes out at the :44 second mark.