A poor, simplistic, country folk, usually of African American descent, who works at larger institutions as a janitor or groundskeeper in maintenance. They are called Mumblies because they mumble when they talk, and are impossible to understand, but somehow are able to understand each other.
Student: Hey the toilets are overflowing can you fix them?
Mumbly: bllrhhargghfahbmbcmlgh! (As he walks to fix the toilets...)