Originally Posted by pigglet

Dress up in a ninja costume, and slip up on her, cock and hand. With your skills of sneakery, wrap her hand around your member, jack off vigorously for that second or so it takes her to realize what's going on, shove her fingers under nose, and exclaim "See, not so bad!!" Run off, stow the fighting gear, and these disavow any knowledge of the incident. Sneak up on her, jack off in her general direction, disappear. After a few months of similar tactics, she might just be so relieved at the notion of "regular nasty-assed perverted" sex that you offer, as opposed to Shiruken, that you end up re-normalizing her expections.

Good luck with that.