BRILLIANT. From Shivani:
When my sister and I were younger, sometimes my parents would have to store items in the fridge at someone's house when we went to visit (such as medicines or milk). To keep from forgetting these items when they left, my dad would leave his keys in the fridge next to the item. That way, wouldn't forget the items in the fridge as he needed his keys to drive home. You probably could do the same at work or school to make sure you don't leave leftovers overnight in the fridge.