You know the summer movies are bottoming out when they resort to the old body-switch premise. On the other hand, David Dobkin's comedy about an uptight family man who magically swaps lives with his free-wheeling bud through that old male-bonding tradition of pissing in a fountain draws on similar themes of duality touched on in such recent films as Crazy, Stupid, Love and The Devil's Double. Here, workaholic lawyer and pussy-whipped family man Dave (Jason Bateman) confronts his discontent at the very start when his son shits in his mouth. When his friend Mitch (Ryan Reynolds) shows up, it's a subversive relief both for him and the audience — Mitch is funny until his character turns into a sad, misogynist troll. After the switch, the film indulges freely in its puerility and disgust with families and women. The real change-up is to platitudes in the end, tough to fall for after watching Dave's wife (Leslie Mann) taking a noisy dump.