Well, not sure. But think about it. As you climb a rope, your genitals are making contact with something. Becoming aroused is probably not all that uncommon. Kind of like 'humping' if you will .As a woman, I think my arms would be burning so that it would be hard to become aroused at such activity as climbing a rope. And female genitals are less you know . . . out . . . to rub on something. But indeed they too become aroused when their genitals are rubbed against something. I'm very sorry to hear about your Grandfather though.