Terrence McNally and Shakespeare Theatre artistic director Michael Kahn have been bosom buddies forever—since long before McNally penned the book for Broadway’s Ragtime. And their joint enthusiasm for opera predates the playwright’s Lisbon Traviata. So a Master Class-type gabfest between them over the Love! Valour! Compassion! and general Bad Habits that make the contemporary theater worth caring about ought to be as much fun as a night at The Ritz. They’ll talk shop at 7:30 p.m. at the Corcoran Gallery of Art’s Hammer Auditorium, 17th & New York Ave. NW. $30. For reservations call (202) 639-1770. (Bob Mondello)