"Hi, I'm Zippy the Pinhead," says Bryce Beyerly, who does an eerily good impersonation of Bill Griffith's legendary cartoon character, "and I'm totally committed to the festive mode." Beyerly wears a polka-dotted dressing gown and a little bow at the top of his artificially cone-shaped head. Zippy is a pop-culture-loving alter ego to Griffy, his creator (a cartoon of Griffith). He lives in a cramped apartment with banal 20th-century furniture -- an easy chair, a microwave, a rabbit-eared TV -- and line-drawing backdrops by, well, Griffy. Or Bill Griffith. But which Bill Griffith? Fun: The Concept not only translates Griffith's cartoon to the stage, it also excavates layers of the artist's identity the way American Splendor (the movie) excavated Harvey Pekar's. We watch Griffy, the cartoon character, open fan mail and wonder whether to sell film rights to Hollywood. He argues with René Descartes about the existence of the self. He picks a fight with a "real" Bill Griffith in the audience. An actor called Mikl-Em plays Griffy with a full measure of angst and mopery, but the reason to see the show is Beyerly's performance as Zippy. The man has obviously practiced Zippy expressions in front of the mirror. He delivers meaningless praises to pop culture ("Reality TV, My Little Pony, and a large assortment of cream-filled snack cakes!") in just the right disturbing tone, and has funny encounters with walk-on characters like the Snowman and the odious Mr. Toad. Be warned, though, that Fun will not convert you to Zippy fandom; if you hate the comic already, an hour in a small theater with a life-size Pinhead may be worse than reality TV.