Rebecca Sugar is a storyboard artist at Adventure Time, but unlike most cartoon shows, the storyboarders are also writers, working from story outlines. This episode had a lot of Rebecca's work and ideas incorporated into it, from this song, to using Neil Patrick Harris as the voice for Gumball.
That's Rebecca singing the demo, and playing her ukelele, which is her instrument of choice. When she was 11 she learned to play the hammer dulcimer, and that's why there's one in this episode! The sketches are original images that Rebecca made to promote the episode, which, in case you hadn't read, scored the highest ratings in AT history.
Also, just to set the record straight, I AM Rebecca's Dad, but I can't recall ever having eaten her fries--and lets be straight here we are talking potatoes fried in peanut oil at 340°, then chilled for 1 hour then refried at 370° for a crispy crust.
