In this essay we discuss a class of apparently metaphorical idioms, exemplified by “fine as frog's hair,” that do not afford any obvious interpretation, and appear to have originated, at least in part, in language play. We review recent trends in both play theory and metaphor theory, and show that a playful approach to language is often an important element in the use and understanding of metaphors (and idioms generally), even when metaphors can be readily interpreted by means of a vehicle-to-topic mapping. Based on this evidence we call for a more deliberate inclusion of language play in metaphor theory and analysis.