Give an honest example. Try to account for how you are working to improve this or how this has been overcome. Think of past criticisms from previous employers, family, friends, and re-word appropriately to apply to the current position you are applying for. The goal is to show that you can recognize your weaknesses and that you are willing to improve yourself on an ongoing basis- ability to take criticism and become better. Be sure not to "shoot yourself in the foot" giving an example that contradicts the role your hoping to get. For example, an in-home nanny shouldn't say she has little patience or has a difficult time with interruptions, loud noises, etc.