Following the last day of school, Fred Figglehorn (Lucas Cruikshank) reveals his hopes to attend Camp Superior, a summer camp that is considered a paradise. Fred's dreams are dashed when he learns his mother is sending him to Camp Iwannapeepee (as Superior was too expensive), a camp Fred finds horrible. At Iwannapeepee, he meets head counselor Floyd Spunkmeyer (Tom Arnold), and a host of other campers, Magoo (Joey Bragg), Chatter (Matthew Scott Miller), Spoon (Leah Lewis), and Dig (Adrian Kali Turner), and is introduced to Oksana (Madison Riley), a beautiful Russian but incompetent camp nurse. At night Fred has disturbing dreams of being at home (with a normal voice) but wakes to find he is still at camp.

Fred learns that Camp Iwannapeepee and Camp Superior have been competing in summer camp games for sixty-nine years and that Superior has always won. He also thinks he has unearthed a plot to drug the food of the Iwannapeepee campers, in order for a giant rat to eat their brains in a place called "The Rat's Hole". Avoiding the gruel, Fred instead eats hallucinogenic red berries, and throws up when the others show up. Fred learns that Magoo, Chatter, Spoon, and Dig go to "The Rats Den" because it's a hideout they've had since being in camp. The "drug" that was put in the gruel was super-vitamins, because the gruel is partially bad. When he learns that his arch rival Kevin (Jake Weary) is on the team from Superior, Fred becomes determined to defeat the rival camp. When the competition begins, Camp Iwannapeepee falls behind in the contests.

After losing to Camp Superior for the day, everyone is down, and Magoo, Chatter, Spoon, and Dig don't even want to go their hideout (The Rat's Hole). Fred, on the other hand, says that they are losers, but they are good at being the best at the bad and good things they do. When the camps play the next day, Fred and Camp Iwannapeepee win the next contests that come up, much to everyone's surprise.

When the singing competition comes up, Kevin and Camp Superior perform a very impressive song-dance routine. When Kevin's cronies say that they should stop Fred, Kevin laughs saying that Fred is horrible at singing (but just in case, Kevin put a big tank of gruel behind the stage to hit Fred with). Fred and Camp Iwannapeepee are nervous at first, but go on stage. Fred starts singing a made-up song of his own called "The Loser Song". It starts making Kevin and the others laugh, but then Fred and the camp perform an impressive song-dance routine of their own, making everyone (except Kevin) cheer. Kevin wants the gruel to hit Fred, but Diesel says it's stuck. Camp Iwannapeepee finally wins The Summer Camp Games and Fred gets off-stage, where Kevin complains saying that "Fred never wins." Diesel's messing with the gruel blaster results in Kevin losing his clothes and being laughed offstage. As the campers leave the camp for summer and prepare to go home, Fred has made some new friends, and his mom has found a new man.