SPAM

It is a well known fact that SPAM actually originated as a way of discreetly distributing new medical products without the public's knowledge. The type of medical product was such that, were the public to know that it was being placed in a food item, they would immediately:

1. Stop eating SPAM, thereby rendering the distribution of the product in question minimal
2. March in large, angry, heavily armed mobs to the factory where it is produced, and proceed to render it and all who produce it nonexistent.

So, the point of all that inane blathering was to give one an idea of SPAM's origins.

Now, once the medical profession ran out of new products (or people to distribute them to, I can't remember which) they began producing SPAM as an actual food. It gained a rapid popularity due to several different conveniences:

1. It was cheap, costing less than one Altairian Dollar per can
2. The can's cuboid shape lent itself easily to storage in cramped spaces
3. The total lack of recognizable ingredients allowed people not to worry about if they were eating anything bad for them

Over time, SPAM grew bigger. Today, the production facilities span the major landmasses of two largish planets (although there is no sign whatsoever of ANY animals being used in production) and is imported to almost every planet in the Galaxy, sometimes without the consumers actually knowing where it came from!