What's a Hoosier?
The first and possibly most popular theory as to why we're called Hoosiers is because a man named Samuel Hoosier, who was contracted to built a canal along the Ohio River in the 1820s, preferred to hire men from Indiana. These men were called "Hoosier's Men," which was eventually shortened to Hoosiers.
A second theory attributed to Gov. Joseph Wright derived Hoosier from an Indian word for corn, "hoosa." Indiana flatboatmen taking corn or maize to New Orleans came to be known as "hoosa men" or Hoosiers.
A friend of mine from Indiana dismissed both these theories. He said the term came about because residents would always ask who's your ma who's your pa.