Johnny unwittingly follows the instructions of a satanic notebook in an attempt to get buff, thus summoning a devil named Derek that enlists him to join on an evil rampage. When Johnny’s attempts to help him end up becoming good things, he possesses Johnny to use his body to wreak havoc on the entire world.

When Johnny agrees to take the initiation trial for the “Brotherhood of the Gnu”, a fraternity that Pops and Carl are members of, he must face the daunting tasks of eating one potato chip and listening to Brother Ernie’s unnecessarily long story of buying a new couch.