Your sister's girl friend is a hot piece of ass, that much is obvious. She shows off her beautiful-looking feet to you and notices how mesmerized you are by them. She decides to open up to you, she wants a guy on the side – the one that likes looking at feet/getting footjobs/worshipping them. Her own boyfriend doesn't fit these requirements, but he's perfect in every other way, so you ain't getting anything more than a few footjobs here and there. Don't you start dreaming about the two of you dating!