One client ask you if you can do irotic massage , what is a best answer?

If the context does not matches with the positiona and irrelevant with its roles and responsibilities, I must avoid the question and politely say that it is irrelevant with the position that will not judge my competencies for the position. So question need to be align with the requirements.  

If you specialise in services related to customer service and it is not in your skills to answer the question say sorry and direct them to a salon for massages.  To be specific in your skills you need to focus on your area specialisation.

Politely refuse by saying "I understand your situation, but unfortunately, that's outside of our control"— focus on the services you are able provide, rather than the ones you aren't.