A Guy Thing

Paul Morse (Jason Lee) (Brother Pete Morse (Thomas Lennon), friend Jim (Shawn Hatosy), father Buck Morse (David Koechner) and Mother Dorothy Morse (Julie Hagerty)) and Karen Cooper (Selma Blair) (Mom Sandra Cooper (Diana Scarwid) and dad Ken Cooper (James Brolin)) are about to get married in Seattle. During his bachelor party, Paul has a chat with one of the dancers at the party, Becky Jackson (Julia Stiles), and they find that they have an affinity for each other. Paul wakes up the next morning and is terrified to see Becky in the bed next to him. Assuming they slept together, Paul rushes Becky out of his apartment and hopes never to see her again. He tries to cover up the connection for the few days before the wedding. Karen is due to arrive at the apartment and to save himself, Paul hides Becky's underwear in the toilet tank. Unfortunately, Becky unexpectedly shows up around town (she is the toll booth collector) and turns out to be Karen's cousin. Ken is upset that Paul didn't invite him to his bachelor's party. Paul works as a marketing exec in Ken's company. Paul realizes that he has crabs and has horrendous itching in his crotch. He visits the pharmacy to get some medicines. He runs into Sandra at the pharmacy. To save his ass, the pharmacist Jeff (Fred Ewanuick) lies that he is a chef and cooked crabs for Paul. Sandra books Jeff to cook the rehearsal dinner for 20 people. At a general family dinner, Paul sees Becky and realizes she is a cousin of Karen. He tries very hard to hide in the bathroom and escape via the trees but trips the car alarm and can't escape. He pretends to have diarrhea to avoid coming out of the bathroom, but Becky circles back to pick her purse (by then Paul was out of bathroom) and both are introduced to each other. The next day Paul tracks Becky down at a music store where Becky tells him that they didn't have sex (he passed out with his pants around his ankles). Becky also says that Paul didn't get the crabs from her, and maybe from the use of a public toilet seat. Even worse, Becky's malicious ex-boyfriend cop Ray Donovan (Lochlyn Munro) had Becky followed and photographed. Ray confronts Paul and asks him to stay away from Becky and reveals that existence of those pics. Karen finds the underwear in the toilet tank and confronts Paul about it. Paul says that it was a gift for her. Karen points out that the underwear is dirty, and Paul complains that the store sold him dirty underwear. Karen confronts the store, who figure out the issue and lie to Karen that some kids played a prank and put dirty underwear in their underwear bins. Minister Ferris (Larry Miller) is Paul's, neighbor and dislikes him as he saw Becky rushing out of his apartment that morning. He also accuses Paul of corrupting his son with pornographic photos, which Paul hides in his crotch as Karen was in his apartment. Paul tries to burn the photos and throws them out of the bathroom window, only for Minister's son to again pick them up and the minister again confronting Paul with a bunch of half burnt photos. Intermittently it is implied that Pete loves Karen and is in awe of her. Pete is divorced and is jealous that Paul is marrying Karen. Becky and Paul meet again to steal those pictures from Ray's apartment. They are confronted by Ray's dog, and they have to hide in his shower. They manage to trap the dog, find the photos and escape via the fire escape stairs. Paul realizes that he is more adventurous and wilder when he is with Becky, who brings out the best in him. Ray arrests Paul after he drops Becky. But at the station, Paul is taken in by internal affairs people, who want Paul to wear a wire to implicate Ray, whom they have been tracking. Paul goes to his rehearsal dinner and tells Becky that the police have put a wire on him to collect evidence against Ray. Meanwhile Jeff, the pharmacist, whom Sandra hired to be the caterer mixes pot in every dish and the entire party gets high. Pete gives an emotional toast where he betrays his feelings for Karen. Karen and Pete remember how they first met each other at a bar. Pete laments that at the time he was married, and Karen got hitched to Paul. Paul returns to his apartment and finds Ray waiting for him. Ray admits that he planted evidence and the internal affairs team moves in on them. The wedding day arrives, and Paul hyperventilates in the toilet with Pete and recounts all the events of the last 7 days. When Pete leaves, Ken emerges from the bathroom. Ken says, "its a guy thing", it happens and tells Paul to move on. Turns out Minister Ferris is going to marry them as their regular priest got sick at the rehearsal dinner. Ferris is totally against Paul marrying Karen. He asks the gathering is anyone believes Paul and Karen shouldn't get married. Paul himself steps up and recounts the events of the last 7 days. He says he doesn't want to marry Karen. Pete steps up and proposes to Karen. Karen accepts. Paul pursues Becky and they hook up.