-- Avenue Q: This tee hee-inducing musical features un-Seaseme Street-like puppets (e.g., a closeted homosexual republican, for starters) and an ode to racism. What's more, the indie production won a surprise Tony Award for best musical, as well as best score and book, beating out Disney's Wicked. It opens tonight at 7 p.m at the Orpheum Theater, 1192 Market; $25-$90.

-- Ask a Scientist: Are you none too bright? We sure are. Which is why we like this casual, long-running Q&A and lecture series that helps us get that much closer to being sharp. Tonight's topic is the reality of age research. Gordon Lithgow (Associate Professor, The Buck Institute) answers your questions at 7 p.m. at Axis Cafe, 1201 - 8th St. (at 16th St.); free.

-- Horn of Dagoth, Lightning Swords of Death, Necrite, Vietus Mortuus: Loud, scary heavy metal. Eeek! Starts at 9 p.m. at Bottom of the Hill, 1233 - 17th St.; $8.

-- Trannyshack (DJ Derek's farewell): After years as Trannyshack's resident DJ, Derek packs his shit and heads to Germany. (DJ Pinky Ring will act as TS's DJ starting next week.) But before he goes, Heklina and her crew throw a show in his honor, "Berlin & Beyond." Music starrts at 10 p.m., show at midnight. At the Stud, 399 - 9th St.; $7.