I know it's fairly common for people to close their eyes when they sing (especially amateurs, especially when singing a cappella), but I know someone, who happens to be a folk musician, who frequently closes her eyes when she talks, for Pete's sake. And I'm not talking about on stage. You can be right in the middle of a one-on-one conversation with her, and her eyes are completely closed. I have never had the nerve to mention this to her, but I find it downright weird.