Make cupcakes according to box directions
After baking move to wire rack to cool completely.
Poke holes in each cupcake
Mix Jello and boiling water stir until dissolved.
Add 1/2 cup cold water and pour over cupcakes.
Refrigerate for at least 15 minutes.
In a large bowl, cream the butter.
Beat in the milk mixing until fluffy.
Transfer 1/4 of the icing to the corner of medium size zipper bag, try to minimize trapped air and close. Clip a small piece off the corner to pipe. Set aside.
Add several drops of green food coloring to remaining icing and mix until color is blended.
Transfer icing to the corner of large size zipper bag. Clip a small piece off the corner to pipe.
Cut each strip of the airheads into 2 1/2 - 3 inch lengths.
Ice the top of each cupcake with green icing.
Pipe a white cloud on each side of the green and insert the airheads strip between them to make a rainbow.