Your pics are pretty small to try to zoom in on. This is either a prolapse or a hemipenial plug. BOTH would need immediate treatment from a vet that knows how to care for reptiles. You want to get plain KY jelly without any additives in it and coat all of the protruding tissue to keep it moist and get him to the vet asap. This chameleon is very thin as well so there is additional stuff going on with him.