Margaret Cho is a funny dame, but its her gleefully vicious portrayal of the oddball outsider thats won the stand-up comedienne legions of loyal fans. Theres nary a trace of compromise or surrender in Chos act, as she ridicules the banality of straight (pun intended) society. Another side of Cho is on display in Bam Bam and Celeste, a 2005 satire in which she and comic comrade Bruce Daniels play bullied misfit buddies who flee their Midwest burg and set out for the Big Apple. Tonights S.F. premiere of the comedy, which Cho scripted, is presented by Good Vibrations. Bam Bam and Celestes belated arrival and brief stay -- coinciding with the films release on DVD -- may indicate that it is something shy of a masterpiece, but the movie counts Chos popular Mommy character in full costume and makeup among its pleasures. As a bonus, the potty-mouthed Queen of Queerdom herself will be on hand to introduce the screening, field questions afterward, and generally tout the pleasures of good, dirty sex.