Read more in “Adventure Time Is a Hit at San Diego Comic-Con” and “Adventure Time Creator Pendleton Ward on Video Games, Zombies and Comic-Con.”

It didn't take long for Adventure Time to become a cultural touchstone, at least for Internet-surfing youth. The wildly popular Cartoon Network series, which begins its fourth season tonight, started out as a viral hit. Since then, it's spawned a lot of cosplay and fan art and probably even more slang.

Though Adventure Time airs on kid-friendly Cartoon Network, as opposed to the cable station's grown-up counterpart, Adult Swim, it's not strictly for kids. In fact, most of the hardcore fans I've encountered at conventions are young adults captivated by the stunningly adorable art and quirky, often subtly meme-referencing humor of the show.

Adventure Time follows a boy named Finn, his dog Jake, and pals like Princess Bubblegum, Lady Rainicorn, Marceline the Vampire Queen and Lumpy Space Princess. They travel across the Land of Ooo, sometimes battling the Ice King and other villains. If you've never seen the show before, you should. Here's why.

7. There's a gender-bent episode.

If you go to conventions or like to sift through fan art online, then you probably know that gender bending existing characters is pretty popular. (Check out our story on the Gender Bent Justice League from San Diego Comic Con 2011.) There's even an Internet Rule about the phenomenon, Rule 63.

The folks behind Adventure Time proved they know what's up with the fans when they swapped genders of their own characters in the episode “Adventure Time With Fionna and Cake.” Finn becomes Fionna, Princess Bubblegum becomes Prince Gumball and the Ice King, naturally, becomes the Ice Queen. The writers then one-upped the online masses by swapping gender and species when they turned Jake into a cat named Cake. While this exceptionally popular episode isn't a regular feature, the show's penchant for picking up on below-the-radar trends is.

6. Lady Rainicorn can make the dreariest day brighter.

When you need some cheeriness, images of rainbows and unicorns can do the trick almost as well as videos of kittens and puppies. This makes Lady Rainicorn the perfect pick-me-up for the end of a long day. The rainbow/unicorn hybrid is Princess Bubblegum's steed. She's also Jake's girlfriend, who speaks Korean unless she's wearing a translation device. She's smart, brave and really good at video games. She can also shoot pixellated-looking rainbow rays out of her horn that change the color of the objects they hit.

5. George Takei has guest starred, and he's coming back.

George Takei, the only celebrity you really need to follow on Facebook, brought his distinctive voice and wit to Adventure Time way back in season one when he played Ricardio, a debonair heart who might very well be up to no good.

Takei was announced as one of the guest stars for season four. Considering that his final line in “Ricardio the Heart Guy” was, “See you guys later,” it's entirely possible that his suave villain may make a return. But, then again, that might not be the case. I'm crossing my fingers for Ricardio's comeback.

4. You can jump right into a cliffhanger without getting confused.

In the season three finale, “Incendium,” Finn is pining for Princess Bubblegum when Jake steps in to find his pal a new girl. He lands in the Fire Kingdom, home of the beautiful Flame Princess. Though the episode doesn't feel like a cliffhanger, it is. Season four starts off with “Hot to the Touch,” which further explores the life of the Flame Princess and her interactions with Finn.

This isn't the first subtle cliffhanger in Adventure Time. The episodes “Mortal Folly” and “Mortal Recoil” form a two-part episode, but you can watch one or the other without being totally confused. With episodes that are short enough to watch during a break at work, the Adventure Time team's knack for writing tight stories that stand on their own comes in handy.

3. Lumpy Space Princess is lumpin' complicated.

Lumpy Space Princess is a floating, fluffy, bloblike girl from Lumpy Space. She speaks in a deep, Valley Girl voice (provided by the show's creator, Pendleton Ward) and has a lot of problems with her parents, some of which may have been avoided if she didn't tell her mom to “lump off.”

LSP, as her friends call her, is a complicated girl. She's prone to sarcasm and, occasionally, meanness. Yet, she complains about her “fake” friends. She's like the popular girl who still feels like a misfit. She also gets into a lot of misadventures, from running away from home to getting caught in the middle of the Candied Zombie apocalypse. The Adventure Time press release mentions that LSP will be writing a “tell-all book” this season. Hopefully, this means that there's more LSP drama this season.

2. Marceline is the coolest vampire on TV since Count Duckula.

Marceline the Vampire Queen is my favorite character in Adventure Time. She's a vampire who eats the color red and, while she's 1,000 years old, she's not that different from a lot of young adults. She loves music and plays a mean bass. Her dad embarrasses her and she has an ex-boyfriend who is an absolute jerk. She's also pretty fashionable and had Skrillex hair before people knew what that meant.

One of the few teasers announced for season four is that Jake and Finn will be heading to the Nightosphere, which is where Marceline's dad lives. Does this mean more of the Vampire Queen for this season? I sure hope so.

1. Finn and Princess Bubblegum have a different kind of hero/princess relationship.

There's a convention of adventure stories that typically involves a princess who needs to be saved and a hero who does the saving. Adventure Time certainly has an aspiring hero in Finn and a lot of princesses, the main one being Bubblegum. Their relationship, though, isn't typical of archetypal pairings. Sometimes Finn saves Princess Bubblegum. Other times, PB, as she's often called, does the rescuing.

Finn and PB have a mutually beneficial relationship. Finn is impulsive and really wants to do good, and those traits come in handy on occasion. PB, on the other hand, is a genius with a penchant for science. Her knowledge and rational attitude often come in handy, except for when she's accidentally unleashing Candied Zombies upon the Land of Ooo.

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