The name of the state of Idaho was originally a hoax.
Idaho was name made up by a mining lobbyist George M. Willing originally for Colorado Territory. He told Congress that "Idaho" was a Shoshone Indian word that meant "Gem of the Mountains." By the end of 1860, Congress was set to name the Pike's Peak region Idaho. However, just as the name was almost adopted, they found out that Idaho was not a real Indian name, but only made up by Mr. Willing, perhaps as a joke, or for local boosterism. Because of this, Congress designated the territory Colorado instead of Idaho.
However, the word Idaho had come into common usage. One of the mining towns in Colorado Territory was even named Idaho Springs, and a steamboat was named "Idaho.". Later on, when miners found gold in the present state area, it became known as Idaho!
Idaho is still referred to as the "Gem State."
It is entirely apocrophyal that the state was named after the remarks made by the first prostitute visiting that august state: "I de ho'!