Spray 2 (13x9-inch) pans or molds with cooking spray.
In large bowl, sprinkle gelatin on tonic water to soften; let stand 5 minutes. Pour one cup of boiling water on the gelatin; stir until gelatin is dissolved.
In medium bowl, mix condensed milk and remaining 2 cups boiling water. Add condensed milk mixture, rum and vanilla to gelatin, stirring until well blended. Pour mixture evenly in pans or molds. Refrigerate at least 6 hours or overnight until firm.
Using lightly greased cookie cutters, cut out ghost. Add pieces of licorice for eyes.