Did you hear the one about the chirporactor at the Middle East peace conference? David Mamet’s new play “Romance” is a rare animal: a very smart play presented in the form of idiotic slapstick comedy. Try to imagine a politically angry “Noises Off.” Or one of the sharper episodes of South Park. Zingers blaze by at a mile a minute, most of them put downs to Jews, gays, Arabs and chiropractors. If you like un-PC humor, you won’t be disappointed.