Today's xkcd:
Mouseover title: "The <x> that is held by <y> is also a <y><x>, so if you go to a food truck, the stuff you buy is truck food. A phone that's in your car is a carphone, and a car equipped with a phone is a phonecar. When you play a mobile racing game, you're in your phonecar using your carphone to drive a different phonecar. I'm still not sure about bananaphones."
See Mark Liberman and Richard Sproat, "The Stress and Structure of Modified Noun Phrases in English," in Lexical Matters, Sag and Szabolcsi, Eds., 1990.
Update — How about other XY/YX English compound pairs, written with or without internal space? There's cat house and housecat; fish-bone and bonefish; index-card and card index; ball game and game ball; dozens if not hundreds of others; how many can you think of within a minute or so?