fuckblunder

Everyone knows at least one of these. They are people who are so stupid, it's a wonder they can tie their shoelaces, yet are arrogant about how 'smart' they are convinced they are.

Someone who think's they're the best and brightest, but literally couldn't hit the hole, so to speak.

Bob: "You have to believe me! I am a leading authority in biblical philosophy and I guarantee you that the world is flat!"
Tom: "You are SUCH a fuckblunder!"