We always say that person's fake if we find out that they're talking about you/someone behind their back. Though a good reason that excuse gets old after awhile and seems to be the only valid thing whenever i hear it. So how would you really describe someone "being fake" in your opinion?
Usually, when someone calls a person fake, it just means that they're not being themselves, or they're trying to put on a persona that isn't really who they are. Behaving in a way to make others like you when really, you are not that type of person.
People who put on a persona around certain people that they don't have when they're alone. Purposely acting a certain way in order to impress somebody or present a certain image that doesn't come naturally to them. Being one type of person, but attempting to present yourself as a different type of person. Blah blah you get it.
To immature people, "being fake" is when somebody who
hates you smiles and says "hi, how are you?" when they're
working behind the counter of the grocery store they work in.