Freak City became one of my fave episodes for two things: one is Magic Man. He's a jerk but he's a creepy but lovable jerk...but I still hate him.
Second reason would be the freaks.
Featuring Gork (the Cyclops), Zap (the ...cloud...fire..thingie), Trudy (The Aqua-girl...or Astronaut, whatever you think she is.), Weewee and Gorflax (The two peanut twins) and Kim (the one with the Syringe)
Adventure Time (c) Pendleton Ward