Cast members from the two shows currently playing the Arena Stage complex -- The Music Man and The Normal Heart, will stick around after performances this Wednesday, July 11. Why? To sing showtunes around a piano, of course. Metro Weekly sponsors the free event, giving theatergoers added incentive to see either show (though you don’t have to see a show to enjoy the showtunes). Wednesday, July 11, at 10 p.m. Arena Stage, 1101 6th St. SW. Free. Call 202-488-3300 or visit arenastage.org.