What you will need:
•Energy Drink (Preferrably Monster or anything that comes in 16oz.)
•2 Bottles of Water
•A good diaper (Bambino, Abena X-plus, etc.)
First, drink the energy drink, then drink the bottles of water (but don't force them down). Within ten minutes, you will have an urge to pee. After you wet the first time, you continue to get urges to pee and be able to wet frequently for the next hour and a half. Eventually your diaper will become very heavy and squishy after the multiple wettings.
Make sure you have plenty of time to be diapered after drinking unless you want to want to be constantly running back and forth to the bathroom. You may also want to be careful with this if you are under 16, as energy drinks say on the label "not recommended for those who are under the age of 16". A cup of coffee or a soda such as Mountain Dew may work almost as good, though.
These can also be done with cheap diapers, but you will need to change frequently as they will leak easily.