An ad-hoc community of fun-lovers turns unsuspecting bars downtown and near the university into impromptu costume parties starting at 9 p.m., Saturday, April 16. Participants dress to the theme "Under the Sea." RSVP required by Friday, April 15. Free. Call (951) 208-3903, or e-mail GMP.Tucson@groups.facebook.com to RSVP and for more information, including the meeting location.