Although they've only been dating for 5 weeks, Dustin (JASON BIGGS) wants to take his romantic relationship with coworker Alexis (KATE HUDSON) to the next level. Having never really dated many guys -- a point brought up by her roommate, Ami (LIZZY CAPLAN) -- Alexis decides they should just be friends.
Devastated, Dustin turns to the only person he believes can fix this problem -- his roommate Tank (DANE COOK). While he works days as a customer service phone rep, Tank -- a chip off the old block, considering his dad, Professor Turner (ALEC BALDWIN), is also quite the player -- spends the rest of his time as a hired gun for various men who want to get back with their ex-girlfriends.
And he does that by being the date from Hell, such an obnoxious boor that the women will go running back into their boyfriends' arms after realizing they made a horrible mistake. Tank reluctantly agrees to do this for Dustin, but is shocked when a drunken Alexis not only doesn't mind his treatment of her, but also wants to have casual sex with him.
He declines the offer, but then finds himself smitten and then falling for her. From that point on, and as Dustin hopes his friend's ploy is working, Tank must figure out how to proceed.