The Kingdom of Loathing is the stupidest game that I've ever been unable to stop playing. It's now been over a year since I joined the kingdom, and I decided that it is time for me to confess my shameful enjoyment of this diversion.
So you're this... stick figure, right? The good king Ralph has been kidnapped from the kingdom by the Naughty Sorceress, and it's up to you to save him. It's kind of a role-playing game, but your character classes have names like "Seal Clubber" and "Pastamancer". On the way to save the king, you'll fight a bunch of badly drawn monsters. Like you'll visit "The Misspelled Cemetary" where you take on "ghuols" and "skeltons." Or you'll go to the Hippy Camp on the Mysterious Island of Mystery, so you can fight filthy hippies and steal their filthy overalls. And at one point, the game temporarily turns into a parody of an old-school text adventure.
The game is riddled with pop culture references -- nearly everything you do will result in 2-4 inside jokes and you'll get maybe half of them. And also, you'll get drunk. You'll get drunk a LOT. In fact, if you are not making your character absolutely as drunk as you possibly can every day, then you're not playing the game to its full potential. Trust me on this one, you'll figure it out eventually.
In the year that I've been playing, I've gone through 19 incarnations of my character, accumulated approximately 1.7 million meat (the Kingdom's unit of currency), and acquired four out of six pieces of rare stainless steel armor as well as one out of six ultra-rare plexiglass items.
What's fun about it is that even though it's the stupidest game you've ever seen in the beginning, it's surprisingly deep because it has multiple levels of gameplay. As you play through the first time, you'll be focused on levelling up your character and experiencing all the wacky things that happen to you for the first time. At the end, you'll fight the epic battle against the sorceress, where you will die a lot but eventually "win". And then you get to ascend to a higher plane of existence, for a short time, before you voluntarily decided to return to the Kingdom and do it all over again.
Once you start getting into ascensions, you get to hold on to all of your items from previous lives as well as permanently save your favorite aspects of each character. You start to appreciate the power to combine skills like Transcendental Noodlecrafting with Saucemastery, while playing Ur-kel's Aria of Annoyance on your stolen accordion and infusing your pets with Empathy of the Newt.
The best part is, it's free! Sign up for a while to try it out. Just one piece of advice though, and I speak from experience. When a shady stranger offers you something in a dark alley, don't take it. You'll be really sorry.