No one talks like that

Is it just me, or the dialog in this movie sounds completely made up, like the writers wanted to create quirky characters and overdid it by 60%. No one is this quirky, no one claps a hand on a girl's mouth to prevent her from venting, no one is this silly and ignorant like an Owen Wilson character, and I can go on and on. The only character who seemed at least a bit probable was Paul's Dad, Jack Nicholson. Even his lines were overexagerated, with the yelling and gesticulating. My point is, the dialogue in this movie could only occur in a movie, people in real life express their feelings and emotions in a much simpler and less quirky way. But that's just me.