e.g. vegetarian meatball.
There are dozens of vegetarian meatball recipes available on the Internet, despite the fact that anything that deserves the name meatball cannot, by definition, be labeled vegetarian. The word meatball is being used to evoke shape, flavor, and the role of the food in various recipes, and what is really meant is something like “a vegetarian version of a meatball.” However, it’s effective to say just the two words, and – if you think of the second one as being in quotes – a vegetarian “meatball,” meaning it’s only a so-called meatball, it works.
Sursa:
http://www.wisegeek.com/what-is-an-oxymoron.htm
peer agreement (net): +4