Commitment-phobic good-time girl Christina Walters (Diaz) is thrown off her stride when she falls for the charming Peter (Thomas Jane) at a club. “The Sweetest Thing” shows some charm initially, but the minute Christina and her pal Courtney (Applegate) hit the road in pursuit of Peter, director Roger (“Cruel Intentions”) Kumble’s movie abandons all sense for scatology, maggots and strained, amateurishly executed slapstick about urinals and oral sex. The movie is R-rated, which means that those who might laugh at these jokes will have to sneak in. Still, Diaz proves once again that she can make the most superficial ditz surprisingly sympathetic, and a very grown-up Applegate shows a wry, deadpan comic finesse that is much better than the material deserves. The filmmakers have obviously studied “There’s Something About Mary,” and learned nothing.
