Even more reviled than a typical roleplayer is a roleplayer who insists on roleplaying. When the dorks need to feel superior, this is the guy they denounce as a dork. Honestly. The only person worse than him is the DM himself.

Make your character's personality vague enough and you can justify any sort of annoying behavior as roleplaying. This is your secret weapon, for it is one which the DM can never take away. Use it as often as possible to wrest the plot from his misguided grasp. When the DM asks you to tone down the roleplaying, you're doing it right. He may not have a SAN score, but see if you can take a few points off of him anyway.