Sheehan's stunt comes five days after another group hired the same company to fly a banner reading, "De Blasio, our backs have turned to you." That was a reference to dozens of cops turning their backs on the mayor at Woodhull Hospital in Brooklyn after Officers Wenjian Liu and Rafael Ramos were slain Dec. 20. Hundreds of cops also turned their backs to a video monitor outside Ramos' funeral Saturday as de Blasio began to speak.