Watching the ViewbyOldDog©
Justine laughed, and then said "none much I guess, except I'm a mess with you shot all over me. I assume this is what they call cum?"
Her grandfather smiled, said "Yes, it is" as he pulled her hand back up and down his penis slowly, "and I'd like you to see if you can coax some more of it out while I enjoy the touch of your hands. As you do that, I'll fill in some of those details for you that you so love to know."
Justine smiled back; this was going to be a good visit for her as she slowly stroked her grandfather's penis into life again. With his help, she would finally be able to sort all this sex stuff out - or be wearing more of his "stuff" again soon. Not a bad trade, all in all.