Parenting Tip #9862
If you have nagged your kid repeatedly all evening to hang up her backpack and it is still on the kitchen floor, walk into the kitchen, absorbed in the argument you are having with your kids, trip over the backpack and swan dive into the nearest wall. No faking, you have to be for real. Once you are done swearing and throwing the backpack across the room, she will quietly hang it up without being asked.
The best part of this technique is that you will have a wicked black eye (and a brutal headache) to guilt her into cleaning her crap up for the rest of the week without you begging.