I actually met David Crosby once. But I didn't know who he was when I met him.
I was a freshman in college, in Nashville, TN. Ironically, my major was commercial music. A friend and I went to a small local music store to check out guitars (him), and keyboards (me). We were in the back looking at stuff, and my buddy looks back at the counter, where a guy was chatting casually with the owner of the store.
My friend goes "Is that David Crosby?" I replied "Who's David Crosby". Marty looked at me like I was an idiot. I figured out later that I WAS an idiot.
Marty walked up and said hi and said he was a fan. I just smiled (like a clueless idiot). The conversation was brief, and David was very friendly.