Had this in pre-k and still remember it! "Mr. Frog Float". Just Ginger-ale or Sprite with a scoop of lime sherbet. This is great for kids, but take away the marshmallow eyes and candy tounge, and add a bit of pineapple juice and lime slices and you have a delicious Lime Sherbet Punch.
Leprechaun-size donuts from Cheerios as leprechaun bait—with printable donut box! Also ideas to lead your kids to believe you've been invaded by leprechauns (green toilet water and little footprints :)