Put two single beds side by side, and the stage is set for a romantic comedy. But what if they are hospital beds? Could a depressing drama be on tap? Not to worry. Rajiv Joseph’s 2009 oddity, Gruesome Playground Injuries, returns to Off-Broadway with plenty of laughs, missed connections, and fleeting kisses. And when things do, on occasion, turn grim, the solid acting, ample stage blood, and traces of vomit make this piece more of a shocker than a bummer. In the reliable hands of veteran director Neil Pepe, it’s a slice-of-life one-act with the emphasis on slice.