Grease and flour a deep, metal mixing bowl or 2.5-liter oven-proof glass bowl. Grease and flour two 8" cake pans. Prepare cake mixes according to package directions. Bake one mix in metal bowl for 1 hour and 15 minutes, or until skewer inserted comes out clean. Cool in bowl 5 minutes, then invert onto wire rack and cool completely. Bake round cakes 20 to 25 minutes, or until toothpick inserted comes out clean. Cool in pans 5 minutes, invert onto wire rack, and cool completely.
Trim tops of cakes to make level. Use 3/4 cup frosting to secure layers together. Place cake on wire rack over wax paper. Heat second can of frosting 10 to 15 seconds in microwave, or until consistency of slightly whipped cream. Slowly pour frosting over cake to cover completely. Scrape up excess frosting on wax paper, and reheat if necessary.
Divide third can of frosting into two bowls. Tint one orange and one blue. Spoon into resealable plastic bags; snip off corners. Place cake on serving platter. To create pants, pipe three lines of frosting up cake from bottom; to make stripes, alternate blue and orange frosting all the way around cake. Using small knife, smooth frosting.
Tint 3/4 cup remaining white frosting yellow. Spoon into resealable plastic bag, snip off corner, and pipe around top and bottom of pants. Spoon chocolate frosting into resealable plastic bag, and snip off corner; pipe mouth and eyebrows on face. For eyes, press on Junior Mints. Divide remaining frosting in half, and tint halves pink and red. Spoon into resealable plastic bags, and snip off corners. Pipe on pink for cheeks and red for the nose. Serves 24.