Mama's Boy is a 2007 comedy that stars Diane Keaton and Jon Heder, and features music by Mark Mothersbaugh. The film was distributed by Warner Independent Pictures for a limited release to certain parts of the United States. Mama's Boy was directed by Tim Hamilton.
Eccentric Jeffrey Mannus (Jon Heder) is 29 years old and lives with his mom, Jan (Diane Keaton). He sees no reason to alter this arrangement, but his perfect world is upended when Jan meets Mert Rosenbloom (Jeff Daniels), a motivational speaker. Mert successfully woos Jan and moves in on Jeffrey's territory, something Jeffrey will not tolerate. While at a coffee shop, Jeffrey finds a friend in one of the workers and later enlists the aid of her as his unlikely ally, an aspiring singer-songwriter, Nora Flannagan (Anna Faris), with an anti-establishment penchant and a soft spot for him. As the war between Mert and Jeffrey escalates, something unprecedented happens — slowly, to both his own surprise and horror, Jeffrey discovers his inner adult. However, before this happens, Jeffrey and Mert get into a fist fight in Jan's home, causing her to break up with him. Jeffrey is pleased, but Jan kicks him out of the house. He goes to find Nora, who is currently upset with him for being such a "jerk", who does not offer any help. Jeffrey lives on the streets, but is eventually arrested for peeing in something that is not meant to be peed on. Seymore comes to the rescue and pays his bail, also allowing him to move in with him. Jeffrey realizes his errors and fights to get Jan and Mert back together. After achieving this he goes to stop the bus that Nora is riding, as she left for college, in his new car. He parks it in the middle of the road and stands on the hood, holding up a radio that is playing one of Nora's favorite songs. The bus driver makes Nora talk to him and they make up. We see them driving off into the distance and the screen fades to black.