How To: Make a Mini-Marshmallow Popper or pom pom popper
Total time: 10 minutes
Knot the end of the balloon, then snip off 1⁄2 inch from the top.
Stretch the balloon over the cutoff end of the cup so that the knot is in the center. (You’ll need to hold the balloon in place when you “pop,” or secure it with a rubber band for little hands.)
Place a mini marshmallow into the cup so it fits snugly in the knotted center of the balloon. While aiming the cup away from you (and others), pull the knot back, release, and see how far you can send the marshmallow soaring.
Source: http://www.realsimple.com/work-life/entertainment/crafts-hobbies/make-a-... [2]