Growing up together, Mitch (Ryan Reynolds) and Dave (Jason Bateman) were inseparable best friends, but as the years have passed they've slowly drifted apart. While Dave is an overworked lawyer, husband and father of three, Mitch has remained a single, quasi-employed man-child who has never met a responsibility he liked. Following a drunken night out together, Mitch and Dave's worlds are turned upside down when they wake up in each other's bodies. Despite the freedom from their normal routines and habits, the guys soon discover that each other's lives are nowhere near as rosy as they once seemed.