Mornin' Swordy!
Blessings upon you.
40,000 dead Cubans couldn't be wrong about him.
Rated TVPG (Parental guidance suggested) and ratings are determined, by episode, by Turner Network Broadcasting.
As for Adventure Time (TV series)'s viewer ratings, those are determined on an episode-by-episode basis by Turner Broadcasting System (company)'s internal S&P group, or Standards and Practices. There's a set division of the company that reviews the content from conception to air, oversees scripts and animation, and, following internal and industry guidelines for every rating demarcation, will then determine what episodes and the show overall are rated. Things under consideration include, especially for children's shows, violence, language, lewdness/sugggestive-ness of adult-like content, and more–there are a number of pages in an ever-evolving guide revolving around sounds of flatulence and what kind of fart noises are inappropriate for air! Broadcast Standards and Practices (US) has some examples of times when S&P groups have intervened to censor content, and the 30 Rock (TV series) episode Standards and Practices (30 Rock) shows a humorous look at the power wielded by S&P.