"Who wants to do something gross? You get to play with water!"
I never would have thought of this, but leave it to my wife to get creative in the parenting department. We were at that point where we absolutely had to clean out the fridge. New products were moving in, old stuff had to go. Of course, there are expired salad dressings and nearly empty salsa jars, and all of it has to get cleaned out so we can be a responsible 21st century family and recycle the bottles.