Barry Egan (ADAM SANDLER) is a plunger salesman who works with Lance (LUIS GUZMÁN) and others in a nondescript warehouse somewhere in Southern California. An emotionally unstable man, Barry is prone to sudden violent outbursts, particularly when harassed by or in the company of any of his seven overbearing sisters, including Elizabeth (MARY LYNN RAJSKUB).
When not plying his trade, he spends his time working on a harmonium that was dropped off at the end of the alley where he works. He's also found a loophole in a frequent flier promotion and thus is buying a great deal of various products, including pudding, that he can redeem for a million frequent flier miles.
A lonely man, Barry decides one night to call up a phone sex service. After giving his personal information to the operator, he receives a phone call from the sultry "Georgia." All presumably ends well, but the next morning she calls back, stating she needs financial help and asks for $750. He says he can't help her, but she insists and starts harassing him over the phone both at home and at work.
It's at the latter where he earlier briefly met Lena Leonard (EMILY WATSON), and now Elizabeth has brought her back in hopes of fixing them up together. They start dating but aren't sure of each other, and Barry's somewhat distracted by Georgia and the fact that her boss, Dean Trumbell (PHILIP SEYMOUR HOFFMAN), has sent a brotherly quartet to get the money from him.
From that point on and as Barry begins to grow as a person, he must decide how to deal with that problem as well as his emotions and feelings for Lena.