Big Valley was such a whitebread vanilla mainstream show, that it's hard to imagine an episode dedicated to tickling, but I do remember one episode where one of the three main guys(I think it was Heath - Lee Majors) was kidnapped by a group of impovershed crazy people and when he was tied up, one of them, a woman, tickled him for a second(no response as I recall). The episode included Leslie Nielson as the leader of the gang. If this is the episode in question, there's not much to it, from a tickling standpoint.