Jackneck
A Jackneck is a person who says dumb stuff and gets the worst slap ever for it.
Jackneck: "I'm gonna be rich." Me: "You're gonna be broke."
Jackneck: "I can beat you up." Me: "You can't even beat me in a race."
Jackneck: "You're the worst." Me: "You're the one who failed math."