Randy Newman, of all people.
A friend of a friend was a marketing director or something at a local theater. She had two tickets that she had offered to someone, but they turned her down so she just gave them to my friend and me on the day of the show. I went in thinking "Meh, this'll be an interesting way to kill some time." Turns out it was an awesome show.
Oh, that reminds me
Back in the early 80's King Crimson came to town. I bought two tickets but I couldn't find anyone else who wanted to go. Everyone said it was going to be a 60's nostalgia show, and that was fine with me - the Crimson King album is one of my all time faves. Anyway, I ended up giving the extra ticket away in the parking lot before the show.
Boy, was I surprised! Fripp, Belew, Levin, and Bruford blew the doors off the hall! It wasn't what I was expecting at all, but man, what a show!