I think my Super Mario Galaxy is haunted. Me and my little sister were playing when I visited and at one point when she had the control Mario slid down two hills and into a black hole. I jokingly said "was it really necessary to slide him down there?" and she replied she hadn't even moved it. I asked to see and the same thing happened, we even put the controllers down completely and the next time he just walked on his own somewhere else, tried to get through/over a fence, eventually got past it somehow and fell down the black hole again. Apparently Mario really can't control his "call of the void" impulses if left on his own.