The SCA has lots of inside jokes and tons of jargon. "A&S" for example, is Arts and Sciences. Here's a glossary that some helpful soul put together. Before your first SCA event, I suggest you print it out and keep it in your pocket in case somebody tells you to go ask the Troll for something.
(If you are a fan of "The Devil's Dictionary" by Ambrose Bierce, you might also enjoy this satire called "The SCAtanic Verses.")