The title is based on the song "Beer For My Horses" by Toby Keith and Willie Nelson, both of whom appear in the movie. Several other past and current country music stars also appear in the movie in cameo roles.
Joe Bill "Rack" Racklin (Toby Keith) is a sheriff's deputy in rural Oklahoma. His best friends Lonnie (Rodney Carrington) and Skunk (Ted Nugent) are also deputies, and together they arrest four men for attempting to steal fertilizer to use to make meth. Rack later learns that one of the men is Mexican drug lord Tito Garza, whose brother Manuel is a cartel leader. Meanwhile, Rack's former girlfriend Annie Streets (Claire Forlani) has returned to Oklahoma from Chicago to care for her mother, who is suffering from Alzheimer's. She is staying at the home of her step-father Buck Baker (Barry Corbin), who runs the largest business in the county and doesn't get along with Rack. After one date together, Rack and Annie re-kindle their relationship.
The next morning, Buck calls the sheriff (Tom Skerritt), saying Annie never came home. Later, Annie's car is found abandoned on the side of the road, with the keys still in the ignition and her purse still in the car. Because of their relationship, the sheriff takes Rack off of her case. The sheriff and all of the deputies then hear from Manuel, who demands that Tito be brought to Mexico or he will kill Annie. That night, Rack, with the help of Lonnie and Skunk, break Tito out of the jail cell and take him to Mexico. Along the way, they encounter a traveling circus, led by Charlie (Willie Nelson), who gives them a jug of their homemade whiskey he calls Circus Jolly.
Rack, Lonnie, and Skunk, with Tito in handcuffs, finally reach Mexico, where they are met by Manuel and Buck. Buck reveals that he is a partner of the Garza's, and his business is just a front for the largest meth operation in Oklahoma. Kidnapping Annie was his idea to lure Rack to Mexico, where he could kill him without anyone investigating it. A shootout then begins between the deputies and Garza's men. Lonnie and Skunk take out the henchmen, while Rack goes after Buck, who still has Annie. While holding Annie, Buck admits to her that he has been giving drugs to her mother to make it look it she has Alzheimer's, but he is then shot by Rack when he tries to kill Annie. With Annie safely back with Rack, he and the deputies take Tito and Manuel into custody.
The next day, after turning in Tito and Manuel to the FBI, Rack, Lonnie, and Skunk are met by the sheriff,. He tells them he should arrest all of them for what they did, but considering the result, he let's them off the hook. The movie ends at the local saloon they all frequent. The entire town is there to congratulate them, and everyone drinks the Circus Jolly with their favorite toast, "whiskey for my men, beer for my horses!"