I was only a toddler during the second world war, but I do have some memories of that time. One was a substance called oleomargarine.
Since most young men had been drafted to fight in Europe and the Pacific workers were scarce and lots of supplies were sent overseas to the military. As a result, there was a shortage of many things in the United States.
One of those things was butter.
A substance called oleomargarine was created and sold in the states to be used as a substitute for butter. It was mostly salted lard and a tiny bag of dye came with it. The dye was orange, but when a housewife squished it into the white, fatty substance with a fork the stuff turned yellow and looked like butter.
I remember watching my mother do that.
Everyone called the fake butter "oleo" instead of using the longer word, oleomargarine.
How my mother hated that stuff! She said it didn't taste like butter at all.
When the war was over some varieties of oleomargarine that actually tasted like butter became available. The common name was changed from "oleo" to "margarine" and many brands of that are available today. Since most of them don't contain animal fats they may be healthier than butter.
But, as long as she lived, my mother would never buy anything but real butter.