Twins are hilarious. Take any story, add a pair of identical siblings, and mirth is certain to ensue. Four hundred years before the adorable antics of Mary-Kate and Ashley and the lovable mix-ups of Tia and Tamara, Shakespeare was making good use of the twin tool in his shortest work, "The Comedy of Errors." Now playing outdoors in the Presidio, Resident Director of the San Francisco Shakespeare Festival Kenneth Kelleher's production is an over-the-top, often raunchy circus of muddled identities, decades and personalities, balanced by the inevitable symmetry of a play based on twins. What it lacks in cohesion is made up for in this farcical production by a high-strung flurry of madness that never cools for a moment nor ceases to entertain.

Although "The Comedy of Errors" is entirely founded on confusion, it is ironically perhaps one of the easier of Shakespeare's plays to understand. Much time is dedicated in the script to explanations of the previous moment's miscommunication, further clarified in this production by the flailing actors, who gesture as if pulled by the strings of an impatient puppeteer toward explanatory labels on the set. Antipholus of Syracuse (Cassidy Brown) sets out with his slave Dromio (Brian Herndon) to find his long-lost twin Antipholus of Ephesus (Bill Olson), who has his own slave named Dromio (Jeremy Vik), creating quite a stir along the way. Each of these four actors does a fine job of mirroring his twin while simultaneously setting himself apart in personality. The entire cast matches the energy of the leads, as they prance about the stage like figures from someone's feverish dream.

"The Comedy of Errors" is rife with countless hilarious jokes, including Shakespeare's many skillful descriptions of the fat ass of Luce, the kitchen maid and "mountain of mad flesh" played by the decidedly non-womanly Gary Martinez. SF Shakes decided to garnish the already amusing original script with a number of timely references to such chuckle-worthy modern muses as the current economic crisis. What could have been an annoying molestation of Shakespeare's writing actually complements the play nicely, to the delight of the easy-going crowd. Even as their fingers slowly froze to their wineglasses in the impending San Franciscan fog, audience members could appreciate a corny allusion or two.

Wine may have been necessary to cope with the piercing voice of Luciana, played by Sofia Ahmad, which greets the audience's ears like a headless Q-Tip. All the actors' voices are particularly cartoonish, but Ahmad's Luciana is a tad too shrill. To be fair, this is the response that Luciana's character is meant to inspire, so that the audience can better empathize with her angular, jealous sister Adriana (Anna Ishida), who is eternally frustrated with her shrieking bimbo of a sibling. Ahmad draws many laughs with her doll-like behavior and is undoubtedly a charming addition to the cast, but she loses several funny lines to her (sometimes incomprehensible) higher register.

Tripping up the pace of the otherwise smooth production, Kelleher inserted several odd pauses from the action for what can only be described as dance breaks. The accompanying music is never quite loud enough to fill the awkwardly sudden silence of the actors. Even in a play so dominated by slapstick, the best moments are always those fueled by dialogue, such as the exchange between Antipholus and Dromio of Ephesus concerning, once again, the unlovely maid Luce's incredible obesity.

In the end, the most wonderful thing about this production is that it's free. This isn't to deny the magic of the play itself-energetic actors and cheeky direction make for a highly entertaining evening. Not that running a theater company these days is anyone's idea of a good way to strike it rich, but SF Shakes is truly putting on theater just to put on theater. They ask not for money, only for the enjoyment of something they love. That is, until the show's end, when the actors leap through the crowd with hats and pleading faces, coaxing twenties from now-well-liquored theatergoers' purses. There's no such thing as a free lunch, nor a free evening of Shakespeare.