When Homer is attacked by a mob of crows, he injures his eyes and Dr. Hibbert prescribes him medical marijuana. Homer quickly becomes addicted to the wacky weed though and starts exhibiting all the known traits of pot-headedness: hunger, laziness, mellowed personality, etc.
While looking for someone to laugh at his company's dismal quarterly report, Mr. Burns hires Homer who finds everything funny while he's high. Burns feels that if he makes the report funny, it'll lesson the blow. Unfortunately, a new law is passed that bans the use of medical marijuana and Homer is unable to laugh at any of Mr. Burns' outdated humor.
At the shareholders meeting, Mr. Burns fakes his own death and Homer and Smithers use his body as a puppet to trick the stockholders. The plan works and the plant is saved from another major crisis.