The reason for this is a lost episode from season 12.
Finding details about this missing episode is difficult, no one who was working on the show at the time likes to talk about it. From what has been pieced together, the lost episode was written entirely by Robert Stainton. During production of the twelveth season, Robert started to act strangely. He was very quiet, seemed nervous and morbid. Mentioning this to anyone who was present results in them getting very angry, and forbidding you to ever mention it to Robert.
I first heard of it at an event where Charlie Ribs was speaking. Someone in the crowd asked about the episode, and Ribs simply left the stage, ending the presentation hours early. The episode's production number was 89502, the title was Dead Little Guy. The episode labeled 89502, Doctor's Pirate Adventure, was made later and given Dead Little Guy's production code to hide the latter's existence.
In addition to getting angry, asking anyone who was on the show about this will cause them to do everything they can to stop you from directly communicating with Robert Stainton. At a fan event, I managed to follow him after he spoke to the crowd, and eventually had a chance to talk to him alone as he was leaving the building. He didn't seem upset that I had followed him, probably expected a typical encounter with an obsessive fan. When I mentioned the lost episode though, all color drained from his face and he started trembling. When I asked him if he could tell me any details, he sounded like he was on the verge of tears. He grabbed a piece of paper, wrote something on it, and handed it to me. He begged me never to mention the episode again.
The piece of paper had a link on it, I would rather not say what it was, for reasons you'll see in a second. I entered the link into my browser, and I came to a site that was completely horrifying-drawn, except for a line of red text, a download link. I clicked on it, and a file started downloading. Once the file was downloaded, my laptop went crazy, it was the worst virus I had ever seen. System restore didn't work, the entire computer had to be rebooted. Before doing this though, I copied the file onto a CD. I tried to open it on my now empty computer, and as I suspected, there was an episode of Greeny Phatom on it.
The intro played as normal, but it had the Simpsons opening theme music played, but it was low pitched. In fact, the episode started off like any other episode, but had very poor quality animation. If you've seen the original animation for Little Guy: The Linebacker, it was similar, but less stable. Act 1 began with the title card in a red background that said "Season 12 Episode 2.5 Dead Little Guy". Act 1 started with Dr. choking on Little Guy. After that, I was startled by a booming sound. To my surprise, the image of Little Guy twitching his hands and keeping his mouth opened suddenly popped up. This happens before going to black.
Act one ended with a piece of unknown text that briefly said "Real suffering is not known" that goes on for 2 seconds. When act two started, Little Guy 2, Dr. Beanson, Dr. and Little Guy are walking in the middle of the nighttime graphics. The colors of Little Guy's face began to change, then goes to multicolor for a second, and then cut to black.
All of this went on for act 2.
Act three opened with Little Guy 2, Dr. Beanson and Dr. standing through a place of tombstones. After all of this, Dr. began to remove his eyes, as if he would be. The episode ended with a still photo of Little Guy 2 twitching his hands and keeping his mouth opened, as much as Little Guy.
The credits were played as normal, and was seemed to be slowed down. During the credits, you can hear an audio clip from Squidward's Suicide. The last 5 seconds of the credits was in black-and-white, and inverted. I did believe what I saw around October 31st (a.k.a. Halloween or Nevada Day).
A thought occurred to me after seeing the episode for the first time, you could try to download this to predict the death of Little Guy, but there's something odd about most of the characters who haven't died yet.
Some of their deaths are listed as the same date (October 25th).