tysout:
Why don't we have a universal emblem or symbol.
How about a nice colorful rainbow sticker? (Oh wait... That one's taken.)
Years ago, gays around here used a little bumper sticker with 3 letters on it. To them, it was instantly recognizable as the logo for an obscure local gay newsletter. Perhaps 1 straight person in 10,000 knew the meaning, so it was the perfect underground code.
I've always called the McDonald's sign "The Golden Buttocks", so I suggest a red, rounded, letter "M". If you are a bottom, turn it upside down.