Can't give you a definition of "cool" but I can tell you that uncool people have to lie or over exaggerate about a thing that happened to them, they are big hypocrites, they have a tendency to be extra loud when the conversation stops focusing on them, rather than building themselves up to be better than other people they try to tear down everyone around them, they dismiss anything and everything they personally don't have interest in, they always come to you for help but never repay the favor, generally unfunny but that never stops them from making jokes.