Bill Bryson is one of the funniest writers alive today. His books are usually travel journals, and so is this. Only he's traveled in time instead of space to tell us about his American childhood.
The Thunderbolt Kid was once his alter-ego. He mentally vaporized parents, teachers and whoever else tried to thwart his childish dreams. He admits that his superhero tendencies occasionally still manifest in daydreams.
When Des Moines gave him the key to the city, officials included The Thunderbolt Kid in his name.