William Selby remembers well when he first heard about a little cabaret show that was generating buzz among New York theater fans. “I was a full-time actor at the time, and I had a roommate who was a waiter at this place – Palsson’s (Supper Club) on West 72nd Street,” Selby said. “He came home one night raving about something called ‘Forbidden Broadway’ and did a number for me. “I fell off the bed laughing – I knew I loved it right then and there.” Selby wasn’t the only one who embraced Gerard Alessandrini’s concept of a satiric revue that both celebrated and skewered musical theater. Since its opening 30 years ago this month, “Forbidden Broadway” played almost continuously in New Yor