Catching up on some Adventure Time while the rest of my family is off visiting their family. On the surface it is a one-note parody of the "in your face awesome!" Saturday-morning cartoon ethos. Think back to the cheesy dialogue of the original Teenage Mutant Ninja Turtles (or Teenage Mutant Hero Turtles if you are British and are jealous that ninjas are so awesome but were invented by a country of barbarians), with constant exclamations of "radical!" and etc.
That aside, the show has tons of funny, smart, and quirky references to roleplaying, fantasy, and video game tropes. And it is so very, very strange. Bizarre strange, more so than practically anything on TV. Hallucinatory, at times. The characters are not quite as likely to break out in song (usually set to chiptune backing) as they are to chop the heads off of some undead elves, but it does happen. And when it does it is often... touching.
The setting is not discussed much but is apparently some post-apocalyptic Earth or similar where magic now works but some remnants of technology exist. Finn the human was adopted as a child by Jake the dog's family. Finn may be the last human on the planet, and Jake can inexplicably change the shape and size of his body. Why? Because it's awesome, that's why.
They typically go on quests. Basically every female on the show is either a princess, a ghost, a ghost princess, or a vampire. Townfolk are made of candy and desserts.
Yeah, the show is pretty strange. And knowing that it is strange on purpose does not diminish the joy of it.