Melissa James Gibson's irritating play concerns four bright young things--a couple of grad students and their boyfriends--whose emotional constipation is manifested in a hopeless inability to communicate with one another despite (or perhaps because of) their exceptional verbal facility. The inadequacy of words can be fertile ground for a playwright, but Gibson's one and only method of exploring it is chirpy chatter about word choice and idioms. Sample exchange: "I'm indisposed." "Do people still get indisposed?" Zachary Davis wisely stages this Appetite Theatre show with a light touch, and his cast demonstrates good (if wasted) comic timing. But there's little they can do to make Gibson's motormouths bearable. --Zac Thompson a Through 12/17: Thu-Sat 8 PM, Sun 3 PM, no show Thu 11/23, National Pastime Theatre, 4139 N. Broadway, 773-275-1931, $15, $30 Sun 11/19 (includes postshow reception).