I can be, depends on the group, but I the dead pan straight man if there isn't one, otherwise, I'm either the one willing to cross That Line, or Mr. Counterpoint, OR BOTH (Those are always entertaining evenings). My favorite verbal tactic however, is to allow someone to leave an openings, and then mention something inpassing while saying not to mention it - thus at the same time crossing That Line, and still not actually having said it, and instead letting people's own imaginations come up with the worst possible internal response. That makes life worth living.
