I call D. "Master" when we're playing. We tried "Sir" for a while, and while he liked the idea of it he asked me to go back to Master because "Sir" reminded him of the character Marcy in Peanuts, the comic strip, who always called her friend Peppermint Patty "Sir."

My submissive girlfriend has started calling me "Ma'am." I can't decide if I like it or not. I like it better than "Mistress," I think.