Start warming up those vocal chords. You know you've perfected "Part of Your World" and "Under the Sea" in the shower.  Now it's time for the big leagues.  Break out the mer-gear, channel your inner Ariel (or of course, Sebastian), and head to The Castro Theatre for a Little Mermaid Sing-Along (Aug. 22-28).  Don't fret if you forget what comes after "each little clam here know how to jam here"- lyrics will  be streaming across the screen (FYI, it's "each little slug here cuttin' a rug here").  And come dressed to impress - prizes will be awarded to the best sea-costume.