A word-of-mouth downtown hit, Titaníque bears more than a passing resemblance to another buzzy show that made it to Broadway, the Tony-winning Oh, Mary! Both projects take a particularly tragic moment in the nation’s history—in this case, the sinking of the Titanic—and tell the story from a different, kookier perspective. But unlike its Broadway predecessor, Titaníque has more than just American history to mine for comedy—it also lampoons James Cameron’s 1997 Oscar-winning blockbuster, Titanic, starring a young Kate Winslet and Leonardo DiCaprio as star-crossed lovers Rose and Jack. As if that weren’t enough, Titaníque also dares to ask this question: What if Céline Dion, the iconic French Canadian chanteuse who sang the movie’s timeless anthem, “My Heart Will Go On,” were actually aboard the Titanic in 1912? And, what’s more, what if Jack and Rose’s fictional love story were set to Dion’s inimitable catalogue, which includes but is not limited to certified adult-contemporary bops like “Taking Chances,” “I Surrender,” and “All by Myself”? With that hyperspecific, insanely stupid premise, Titaníque set sail. Of course, an …