-------------------------------------------------------------------
I figured these out on a ukulele, so they may need tweaking for guitar.
I don't play guitar, so I have not tested them. 
If they are not quite right, please let me know and I will update the chords. 

I am not 100% sure about these, but they sound good when I play it.
-------------------------------------------------------------------

  G 
Adventure Time 
     D
Come on grab your friends 
      C
We'll go to very 
D
 Distant lands 
     G
With Jake the dog 
    D
And Finn the human 
    C              D
The fun will never end
               G
It's Adventure Time!

        D
Hey Ice King 
                    C
Why'd you steal our garbage? 
               Eb
Pretty sure we didn't 
D               G
Ask to have our garbage 
      D
Taken away 
               C
By some cranky ice janitor 
D                G
 Just who do you think you are?!

Em          G
You king of ice 
         Am7
It would suffice 
            D7
If you'd be nice 
             C
But you're a jerk! 
         G
Probably want to 
        A
Build a girlfriend 
           D
Out of the garbage! 
C                Am
 Now that's just crazy talk 
Em
Nobody'd be that crazy 
     C
It's probably something else.

D7

G        D
 Hey Ice King 
                   C
Why'd you take our garbage? 
               Eb
Really can't remember 
D             G
Giving you permission. 
               D
Where could it be? 
             Em
Gonna go and find you 
                      Eb
And I promise when we find you 
      D7       
Gonna take you out!

Em            G
  You king of cold 
           Am7
Stop being bold
             D7 
It's getting old
          Em 
You turbo-nerd! 
        G
Can't believe you'd 
          A
Steal our garbage 
               D
From under our noses. 
C                Cm
We'll get to the bottom of this 
G         Em
Don't you worry, 
C                                D   D7
 We'll get our stuff back in the end.

G        D
 Hey Ice King 
                    C
Why'd you steal our garbage? 
               Eb
Pretty sure we didn't 
D               G
Ask to have our garbage 
       D
Taken away 
               Em
By some cranky ice janitor. 
D               G
Just who do you think you are?!