There is only one "Just William". The loveable imp and his band of Outlaws have been harassing his unfortunate family and delighting hundreds of thousands of readers for years.
Here William invents a water race where competitors have to run with a mouth full of water, without swallowing it or spitting it out. It's just a shame he doesn't have time to think before speaking to (and drenching!) Mrs Adolphus Crane during the race!