Problem... solved.

I was home, holding down the fort this morning, while my dad took my mom and brother to the airport... I made a nice little lunch and the kids then had a nice little dessert of vanilla wafers with leftover whipped cream on top. Seeing that the canister was nearly empty, Nathan had the sudden urge to shoot it with his pellet gun and witness the foreseen explosion. He forthwith took his pellet gun and target outside, and all the little one watched as the can fulfilled his expectations.
The girls who hadn't liked the idea to begin with, set up a loud wail, crying "He wasted all the whipped cream!" Bethany even went so far as to say "I could have made a meal out of that!!" *sniffle* ...and believe me, they were serious... crying over spilled milk? The figurative idiom was manifested quite literally before my eyes.
I figured the best solution would be to let them burn off some steam, rather that beat them over the head with common sense. However, as the boys continued to play outside in their midst, the girls found sufficient fortitude to carry on for quite some time.

Now I thought to myself, "Is a tablespoon of cream such a precious resource? We have sitting in our fridge at least a quart of the stuff, with no immediate purpose."

I then poured a tablespoon of the heavy whipping cream from our fridge onto a pretty little saucer and called my resentful little sisters inside, saying, "Here on this plate is the same amount of cream that was 'wasted'. Eat it, then go outside and play."

Problem? Solved.