Sandy is a squirrel from Texas who lives in the Treedome. She is the only land creature who lives in Bikini Bottom, and she wears an air helmet while she is in the water so that she can survive. Always in a good mood, Sandy is very athletic, friendly and well-liked. She is very understanding, and is clearly the smartest of the characters on the show.
I believe Sandy is actually at the 5th level of moral development. She not only believes that rules should be followed, but she also always tries to be fair. She is very forgiving, which one needs to be when one has friends as immature as Spongebob and Patrick.
In Ripped Pants, Sandy sees through Spongebob's competing with her for the attention of the other beach-goers. Instead of getting angry at his childish behavior, she says to him, "If you want to be my friend, just be yourself." In the episode Squirrel Jokes, Spongebob tries his luck at being a comedian and never succeeds. He finally gets his audience to laugh by telling a joke making fun of squirrels. After that, he only tells squirrel jokes because they are all that get a response. These jokes greatly hurt Sandy's feelings, but she allows Spongebob to enjoy his success. She explains to him after the show that his jokes are very insulting to her, and he now has the whole town mocking her left and right. She eventually gets him to understand that it is more important to not hurt her feelings than it is to get a good audience response. I see this as a good example of Sandy being at the 5th stage of moral development because she responded well to her own hurt feelings and respected Spongebob's feelings when she spoke to him about it. She did not get furious with him, she just wanted his jokes to be fair. In the end, Spongebob wound up telling jokes about sponges.
