A man who isn't afraid of anything. Meaning, he's not afraid of any danger, (death included) not afraid to speak the ugly truth, and isn't afraid to take it in the balls and still stand tall like a proud gentleman should.
Guy 1: "Did you hear, Joe called Leslie an ugly horse face b**ch. Then, she knee kicked him in the balls!"
Guy 2: "Does that guy have a death wish or something?"
Guy 1: "Nope, that Joe is a real soldier. He even asked her to kick him in the nuts again."
A person who claims to know everything about everything, until someone else calls their bluff and makes that person look like a fool. Basically, a know-it-all with ridiculous assumptions and little-to-no proof.
Guy 1: Did you know that this new game console was coming out, during the Summer time?
Guy 2: Stop right there, you stupid know man! I just found out from the creators, they said they plan to release said console sometime during the Fall.