The real reason for calling this small dish a "monkey dish" has been lost.  The stories in the other anser as as good as any.  They has been repeated again and again on the web (but this does not make them any more reliable).\nOthers have associated this dish with the "ramekin."\nSee the first three sites below.\nThe most reliable source that I could find states:\nThere are questions for which there are no satisfactory answers (Who named the "monkey dish?").  See the final site.
in the food service industry, there is a small vegetable dish that is called a monkey dish, Why?