Don't be surprised if a ''genuine accident'' doesn't happen to you. Most people with normal bladder control don't wet themselves that easily. You might find yourself just giving up and letting go voluntarily from the discomfort of a full bladder before you actually have an accident.
The one and only time I did a major hold, I just drank normally all day, and was nowhere near having an accident hours later, although that wasn't really my intention. I just held all day then peed outside for the first time.
There's a lot of advice floating around out there about how to make yourself desperate. I'd say the easiest way is to simply drink a quart of liquid over a one-hour period. I know this because before you have certain ultrasounds you need to have a full bladder and they instruct you to drink that much water. The last time I had to do it I was miserably full after about three cups of water and Gatorade and an hour or so (although still nowhere close to losing control).
