In a large saucepan, melt butter over medium heat. Add marshmallows and stir until completely melted.
Stir in Rice Krispies and stir until well-coated.
Pour mixture onto a lightly greased 16" pizza pan. Grease hands and begin forming Rice Krispie treat into the pan. Curve the edges to make it look like a pizza crust.
Spread red frosting evenly over the treat, leaving the crust without frosting.
Lightly sprinkle the treat with shredded coconut while the frosting is still wet so the coconut sticks well.
Use a rolling pin to flatten the airheads. Cut the red Airhead into circles with a water bottle cap. Cut and shape the green Airheads to look like green bell peppers. Press gently onto the treat.
Slice into 8 pieces with a french knife to serve.