What is green cheese it has fat?

You're likely thinking of green cheese as a slang term for something that is not real or believable, like a "fairy tale" or a "pipe dream". It's often used humorously to describe something absurd or unlikely.

The phrase "green cheese" likely originated from the idea of the moon being made of green cheese, which was a popular folk belief in the past. It's been used in stories and jokes for centuries to represent something fantastic or unbelievable.

There is no real cheese that is green in color due to fat. While there are some cheeses with a greenish mold (like Roquefort or Gorgonzola), they are not green due to fat, but because of the mold growth.

So, if someone tells you something is "green cheese", they're probably trying to tell you it's a ridiculous idea!