To swing wildly between extreme positions, bobbing between them, as it were.
Jenna: "Woah dude, last week you told me those sweet new roof racks were going to turn your life around, now it's the end of the world cos your paint job got scratched."
Craig: "It's true! My life is over!"
Jenna: "You gotta stop being so hyperbobolic, it's bad for your blood pressure man."