Repairman Question:

Three words describe how you should answer this question: Relevance, relevance, relevance.

But that doesn't mean you have to make up an answer. You can learn something from every job. You can develop skills in every job. Work backwards: Identify things about the job you're interviewing for that will help you if you do someday land your dream job, and then describe how those things apply to what you hope to someday do.