spam is spiced ham and humans being the lazy things that they are thought that saying spiced ham all the type of would be too much so they shortened it to sm. Then later it was found at that people were having a lot of trouble saying sm so they changed it to fish. Fish, as you may well know, was also a name for something so this just lead to a lot of confusion. So they decided to change the name of fish (the original) to spam. This didn't work either as people who didn't know about the change were ordering spiced ham when they wanted fish and those who did know about the change usually had very bad memories or incorrect change. Finally the people snapped and while they were being put back together a clever little civil servant changed the name of spam back to fish and fish to spam. So that is how spam got its name and explains why you get cod in certain parts of the country when you order spam.