What I like about this snake image is the way in which it’s playing on the idea of snake = rampant sexuality. The joke is based on the notion that untrustworthy men are known colloquially as snakes, which is an idea that goes all the way back to the idea of the serpent tempting Eve with lies (there’s also a phallic connection, but I think that’s slightly less relevant right now). A snake is untrustworthy because a) it damned us all in Judeo-Christian thought, and b) it can shed its skin – start anew in a way that people can’t. The cartoon plays on both of these notions: the woman is being betrayed by a snake once more and the snake’s assumption that because it’s a snake, she should have expected his behavior.