LAUGHTER ON THE 23RD FLOOR, Briar Street Theatre. Neil Simon’s 1993 play takes place in the skyscraper office of a TV comedy series, where any subject is ripe for a joke–except communism. It’s 1953, and as one character says, there’s “a wait list to get on the blacklist.” The witch-hunting antics of Senator Joseph McCarthy have engendered too much anger and paranoia among the creators of NBC’s weekly Max Prince Show to encourage much joking, so Lucas, Ira, Kenny, Val, Carol, Milt, and Brian–Simon’s surrogates for himself, Mel Brooks, Larry Gelbart, Mel Tolkin, Selma Diamond, and other young writers for Sid Caesar’s Your Show of Shows–train their satiric sights on outrageous but irrelevant movie parodies and sexist domestic-squabble sketches. Meanwhile the Caesarean Max Prince tries to stall network honchos who want to trim his budget, his running time, and his style of humor, deemed too urban and Jewish for increasingly suburban America.