Me: “I’m told I need to rudely importune you if I want to sing”
He: “Ooooh! I love being rudely importuned! I see you’ve come as Cleopatra”
Me: “Looked like a classy gig. If in doubt, overdress, I thought”
He “It’s a good look. Don’t think we’ve met – what’s your name? I’m going to put you on first”
This is how Jazz Jam Sessions work: you just turn up, talk to the guy, and they put you on with any luck. You’ll need your own sheet music, at least 3 copies, unless it’s a well-known jazz standard, in which case a chord chart will do.