It meant "un-cool" or not current with popular fashion and behavior.
Jerk IS a slang term. It means a person who doesn't care about anyone and is rude or mean to everyone. I can't find any specific slang from 1950 that means the same thing.
A square is a person who is not "cool" or "hip." This would be the person who is unpopular and does not follow the latest fashions in clothing, slang, and behavior. "Square" is an old slang term from the 1960's.
"Fresh" or "minty" would be 1950's slang terms for new.
In the 1950's, hop was slang for a dance party or social gathering where music and dancing were a central focus. It was a term commonly used to describe informal events where young people would gather to have a good time.
fruit
There are 88.2579 square meters in 1950 square feet.
Platters.
The gang.
If you mean slang as in internet slang, then it means "Certified Old Fart".
In the 1950s, the slang term "cube" referred to a square or block-shaped object, particularly in the context of marijuana use. It was often used to describe a small, compact amount of the drug. Additionally, "cube" could also refer to a person who was considered dull or uninteresting, akin to being "square."
It means you're old-fashion and you always follow the rules. Pretty much you won't take any risks and your "square" is your comfort zone.
Saturday Square - 1950 was released on: USA: 7 January 1950