It's not one joke, it's a complete hodge-podge of random, stupid, poorly thought out, disconnected, and overall annoying jokes that ruins the game's humor.
Why do I mention it as one of the worst games ever made? Not just because of that and the boring, by the numbers gameplay with no real interesting quirks or decent gameplay mechanics, but almost everything else about the game is generally unlikeable too, including the graphics and the OST. I've heard the argument that the graphics were good for their time, but honestly I strongly disagree. To make matters worse, it's a game that I'm basically forced to play again and again and again because the fanbase thinks I should give the game another chance, but the more I play it, the more it's "by-the-numbers" gameplay makes me want to sleep. I could almost forgive this if it wasn't for all the people who are like "NO! You are not allowed to hate this game! It's a GOOD game because we said so! YOU MUST LIKE THIS GAME!!!" Sure, it doesn't have any glitches or anything like that, but I sure as heck didn't have fun playing it.
Yeah, I know what you're thinking of doing. You're going to try and play the "YOU MUST LIKE THIS GAME" card around on me because of Skylanders. No, I'm not saying you have to like Skylanders by any means, I'm just saying at LEAST try the game before saying you truly hate the game. I have no problems with people disliking a game if they've actually played it. Most Skylanders haters, however, have not.
...Just for the record, though. I wasn't the one who mentioned Earthbound. I was just discussing it. Again, I don't know about "worst game ever" bad, but I do dislike Earthbound more than just about any other game I've played.