On the frozen wastes of Antarctica, a mother-to-be Adélie penguin sells her body for stones. In deepest, darkest Africa, chimpanzees trade meat for sex. In Canada, a post-hibernation gathering of garter snakes becomes a frenzied orgy. A redback spider eats her partner alive while they're still mating. Are these animals behaving badly? Or is the drive to reproduce so fundamental in the animal kingdom, that "anything goes"? Meet the world's weirdest friends with benefits.