FRIDAY: >>Do you like Hall and Oates and Haddaway? Who doesn’t? The Black Cat is hosting Crap, a dance night of bad music on purpose. We advise loosening your Macarena muscles and preparing your ears for “singers” like Don Johnson, Eddie Murphy, and Bruce Willis. 10 pm, free. SATURDAY: >>There are more art openings than we can shake a sculpture at today, so check out our Arts Agenda for a rundown. >>Anything called “Underwear Party”…