Inside jokes are the only things theaterfolk love more than applause, so no surprise there’s been plenty of insider art inside the Beltway lately. A year ago, Urinetown earned itself a raft of Helen Hayes Awards for its watertight parody of pretty much every musical melodrama ever produced; Arena spun dizzily through the classic backstage farce Noises Off last December, and for another night or two there’s a sublimely lunatic trip to be taken courtesy of Woolly Mammoth’s more-than-meta-theatrical She Stoops to Comedy. Do yourself a mood-altering favor: Make She Stoops your Saturday-night outing, then make a weekend of it with a Sunday trip to Metro Stage, where a sharp cast and a slate of wickedly on-target musical spooflets are waiting to send you off into the work week with a bounce in your step and a big, stupid grin on your face. The show is The Musical of Musicals: The Musical!, and it’s even less reverent than it sounds. Composer Eric Rockwell and lyricist Joanne Bogart take a tawdry little story—about a rent-challenged girl and the villainous landlord and virtuous boyfriend who vie for her affections—and tell it five times, in the styles of Broadway’s biggest musical names. Jerry Herman, Rodgers and Hammerstein, Andrew Lloyd Webber, Kander and Ebb, and even that sacred musical-theater cow Stephen Sondheim get lampooned and spoofed and outright mocked—so thoroughly and mercilessly mocked that the creators can only be passionate devotees. Rockwell and Bogart demonstrate a keen ear for the musical tropes and the lyrical signatures and the showbizzy tics of their hero-targets, and the more pointed their teasing, the funnier: From the pie-eyed opening parody, “Oh What Beautiful Corn”—it’s Kansas in August, and Mother Abby exhorts beautiful June to follow her dream ’til she’s dead—to the keyboard vamp over which a bored androgyne welcomes the crowd to the speakeasy in six or eight languages, including Hawaiian, the authors roll out pastiche after deft pastiche. None’s more satisfying than the layer-on-layer Sondheim sendup, set in a Manhattan apartment complex, ahem, rather than anything so psychologically pedestrian as a mere apartment building. The performers, especially Donna Migliaccio and Bobby Smith, are on fire, and Larry Kaye’s snappy production works like a charm: Civilians will giggle merrily, if only because the theater geeks in the audience will be shrieking with glee.