"So It's Come to This: A Simpsons Clip Show" is the eighteenth episode of Season 4.
Bart's April Fools' prank backfires and lands Homer in the hospital in a coma. At Homer's bedside, The Simpson family reminisces about all of the good times they've had over the years. This around the time Al and Mike wrote The Critic pilot.
The story begins on April Fools' Day. Homer is playing pranks on Bart throughout the day, including putting duct tape over his eyes before he wakes up, and placing sour milk in the refrigerator for Bart to take. Bart, angered by the numerous tricks he has fallen for, attempts to get revenge by shaking up a beer can in a paint shaker. When Homer opens the beer, it results in a massive explosion that severely injures him. Homer is then driven to the hospital. Dr. Hibbert (via a cruel April Fools' Day joke) explains that Homer is alive, but he may never be able to walk again. The Vet explains some aspects to Homer's health and injuries that he suffered before Marge recognizes him. While visiting them, Barney then attempts to ease Homer's pain by suffocating him with a pillow and escaping which causes Moe to think that he needs a girlfriend. Homer is eventually resigned to not being able to walk again, until he notices a candy machine on the other end and begins to walk. Unfortunately, he ends up getting a lot of candy bars in his mouth from forcing it to come down, thus placing him into a coma.
As the family visits Homer, they reminisce about the events they have experienced in the past (clips from previous episodes). Mr. Burns also attempted to "pull the plug" on the vegetative Homer. During this time, he shows signs of life. Eventually, Bart confesses that he made the beer explode. An outraged Homer wakes up and strangles his son while the rest of his family stand next to the bed, relieved he is finally awake (Marge tells Homer at the conclusion of the story that the current date is May 16, and that Homer was in a coma for weeks, and that he lost 5% of his brain).