a moron, an idiot, a major poser, a pretender, a dumb-ass, a freak
to make a stupid or idiotic mistake that could have easily been avoided
a person who believe he/she is sexually actractive and boasts about it but in reality is not
one who makes fowl-ups in sports/video games
someone who is clumsy and just makes stupid mistakes
someone falling flat on their face while running from a mad man after teepeing his house because they were too busy looking back would be called a "scrub"