When they get beyond a certain age, female actors don't often have much fun onstage. Relegated to playing doddering old dowagers, even the spriest sixtysomething must resign herself to spending the rest of her career serving tea from a samovar to bored Russian aristocrats, or bellowing "A handbag?!" at the top of her voice. Thankfully, playwright David Lindsay-Abaire somewhat readjusts the balance with this spiteful-sweet comedy. As depicted by the vivacious Joy Carlin in SF Playhouse's production, Kimberly, a teenager suffering from progeria (a disease that produces rapid aging starting in childhood), is one of the funniest and most complex roles for an older female actor on the contemporary stage. Surrounded by grown-ups so dysfunctional they make Homer Simpson look sensible, the wrinkly 16-year-old character becomes a grotesque metaphor for the ravages of time and a lost childhood. Featuring lurid performances by Clive Worsley, Susi Damilano, and Deb Fink as the "adults," a lovably gauche Jeremy Kahn as Kim's geeky friend Jeff, and vibrant candy-colored lighting by Jon Retsky, director Kent Nicholson's production hints at the sadness under the zany, comic-book exterior of Kimberly's existence.