On this day in history, July 5, 1937, Spam, the luncheon meat, is introduced into the market by the Hormel Foods Corporation, but it didn't really catch on then. It would achieve most of its notoriety in WWII as military rations.
Most of the Spam eaten by soldiers was actually government meat that was canned by Hormel and other companies that were under contract to the military. Only a few soldiers received genuine Spam, but it was Spam that they came to know and hate. They felt like they had Spam for every meal and ran out of ways to prepare it. The universal dislike -- they wrote songs about how much they hated the stuff -- probably had less to do with the actual taste of Spam than with how often they were forced to eat it.
Nevertheless, the soldiers brought a taste for Spam home with them. And by prominently featuring the brand name on the packaging and spending lavishly on advertising, Hormel succeeded in making Spam a household product in the United States.