The Super Soaker was invented by an engineer who wasn't trying to make a toy.

In 1982, aerospace engineer Lonnie Johnson was testing a new heat pump when a powerful stream of water shot across his workshop. Instead of seeing a failed experiment, he saw a better water gun.

Johnson built a prototype from plastic tubing and a soda bottle, then licensed the invention to a toy company. Renamed the Super Soaker, it became one of the most successful toys ever made, generating more than $1 billion in sales.

Not bad for an idea that started with a leak.