It's half an alter boy outfit and the guy off stage playing guitar is dressed as a priest (other version: http://www.youtube.com/watch?v=PPVRm5hAqOA). It's a naughty, naughty, racy, tongue in cheek cabaret act that he was a part of. From what I've been reading his was one of the more TONED DOWN performances.

I loved that show. So much. It was my second fandom and such a... calm fandom.