Two unemployed, 40 year old Los Angeles area slackers - Brennen Huff (Will Ferrell) and Dale Doback (John C. Reilly) - are brought together when Brennen's mom falls for and marries Dale's dad. As the two get used to living together, tensions between Brennen and Dale grow incredibly intense. They soon decide that they both have the ultimate business idea, combine Brennan's singing abilities with Dale's drumming abilities to form a rock and roll karaoke company.
However, Dale's father's dream of sailing around the world hinders their plans, along with a series of incidents that constantly shoot themselves in the foot. Can they pull it off without driving each other completely crazy?