And by “surprise”, I mean omfg surprise.
I went to see a friend of mine’s band play at a large local venue. Another buddy and I showed up early and proceeded to play pool and get sloshed for an hour or two.
Right at about 10:30, my friend from the band comes to find me.
“The opening band flaked out on us. You and me, on stage, five minutes.”
So I got to play an unexpected gig at a large, crowded show, hammered off my ass, with no practice whatsoever, and five minutes warning. Awesome. There are times when you crank the distortion to 20 and say Damn the Torpedoes.
I’m sure it sounded like dookey, but we got applause, and it sure was fun. 
Oh, and during the real band’s set, they surprised me again. They had worked up a version of a song I wrote about 20 years ago, without me knowing it. I got props from the lead singer, and took a bow for the audience.
It was a Good Night. 