Are bike messengers born or made? Among the ranks of self-identified martyrs, there's no more determinedly antiheroic figure, or more fiercely voluntary social exile. Writer, performer, and messenger Tony Mendoza has a great handle on the comic contradictions of the typical two-wheeled warrior's goofy/grave persona, and is immensely watchable as the anchor of this urban picaresque. His supporting cast of seasoned sketch and improv players handily flesh out a rogues' gallery of asshole grotesques, and director Pat McKenna keeps things ticking along at a steady clip. This is pretty funny as bitch-about-my-job, trials-and-tribulations tales go; ultimately its shop-talk specificity gets a little wearying, and the story deliberately goes nowhere, but it rings true all the way through the realistically desultory finish. Through 9/28: Thu 8 PM, Annoyance Theatre, 4840 N. Broadway, 773-561-4665, $7, $5 for bike messengers with I.D.