Sanity is a blue lemur. He is insane and is commonly seen in asylums, wearing his signature straitjacket.
His favorite hobby is killing people, or trying to thereof, as his straitjacket makes it difficult for him to do anything that requires arms. Thus he will often commit to the oddest ways to kill. At other times, Sanity will struggle to get his straitjacket off (which is rarely done), at which he is most vulnerable to accidents.
Unlike Flippy and related characters, Sanity does not flip out. He is always insane and homicidal. He has a trademark maniacal laugh, usually heard when he escapes or kills someone.