What is the origin of spam musubi, a Hawaiian dish?
Spam became prevalent in the US occupied Pacific islands during World War 2 since fresh meat was difficult to procure at the time.  Since it was a primary food staple, it was incorporated into various dishes, and has remained a popular food.  Spam musubi is just an an extension of this.  Making do with the meat available to create a tasty dish, obviously influenced in this case by Japanese culture.