Allegedly Optimistic Ending: While Arthur had apologized to Sue Ellen and repaired his friendship with her, he still did irreparable damage to his reputation for bullying Sue Ellen, and his friends might never look at him the same way again.
Alternative Character Interpretation: When Buster was "not very good" at giving Arthur the Silent Treatment — was this because he's naturally friendly and so being antagonistic doesn't come naturally to him, is it because Arthur in particular is his best friend so he has trouble making himself antagonise him in particular, or is he just scatty and forgetful and so has trouble remembering not to speak?
Broken Aesop: This episode's Aesop is supposed to be about bullying. Except that Arthur (not to mention George) has been a Bully Magnet for years... and nothing was done about it. Is it any wonder that he thought this was acceptable behaviour? Also, in "Meek for a Week", Francine's friends were portrayed as being in the wrong for telling her not to be rude.
Broken Base: The episode is divisive among the fandom, since while pretty much everyone hates it, there's debate over whether Arthur was truly being a bully and thus the episode is bad because he was out of character, or whether Sue Ellen really did overreact and she was the one being out of character for being so offended by the jokes, and Arthur's friends were the ones being mean by giving him the Silent Treatment and calling him a bully over what were ultimately a few Innocently Insensitive jokes.
Don't Shoot the Message: The Aesop against bullying, especially the message of how teasing can go too far (even if you don't intend for it to) and that a "Just Joking" Justification is not an appropriate apology, is a good lesson for the show to have. However, the reason why this episode is widely disliked is due to how there were several characters going against their usual personalities in order to deliver this messagenote In particular, one of the friendliest characters (whose previous biggest Jerkass Ball moment involved punching his younger sister after being pushed to the absolute limit by her behavior, even after giving her several verbal warnings) bullies a girl to the point that she seriously considers permanently switching classes just to get away from him, which makes the lesson come off as awkward.
Fanon Discontinuity: Good luck finding anyone who likes this episode, especially for its derailment of Arthur into a bully who mocks Sue Ellen's sweater.
Ironic Episode Title: "So Funny I Forgot To Laugh" is probably one of the most depressing episodes of the whole series.
Never Live It Down: Many fans have not forgiven Arthur for bullying Sue Ellen over her sweater, despite him normally being a genuinely Nice Guy as well as the fact that he showed remorse and apologized at the end.
Tear Jerker: The teaser actually sets up the story well as Sue Ellen explains how much her sweater meant to her, but now she can't feel good when she thinks about it because of the bullying she received. It's a surprisingly subtle and well-written scene compared to what follows and is generally agreed to be the high point of the episode.
Unintentionally Sympathetic: Arthur himself. Considering that Francine, Muffy, Binky, and even Buster have done worse to him without so much as a talk from Mr. Ratburn or any other adult or anyone else standing up for him, it just makes everyone else come off like a bunch of people who can't give what they dish out.
Unintentionally Unsympathetic: Arthur's friends giving him the Silent Treatment and calling him a "bully" was meant to be him getting karma for taking his teasing of Sue Ellen too far, but some of the viewers thought that this was meaner than Arthur's dog jokes, especially with Francine and Muffy, who were seen by some as hypocrites since they're usually mouthier than Arthur.