Nico Robin notices you starting at her tits and ass. She doesn't say it but she likes the way you look at her. You don't know this but she has devil fruit powers that makes arms appear anywhere. Later when you are alone with her she uses her devil fruit power to help you get off while she touches herself.

This is what I would do with arms devil fruit powers hehe.... This is basically the premises of my new roleplay video coming out Friday!!