Lisa was as suprised as her sister with what was happening between them.  Lisa wanted to say something like, 'I'll stop if you think we should' but at this point, she didn't want to jinx whatever the hell was happening.  It was almost like instinct, animal magnetisim.....they were sisters but for some reason it felt so right....Cassie's skin was so soft, so supple and her body was so yielding to her advances that one thing seemed to naturally follow another.<br/>Lisa pulled off her panties and they were now naked, their warm bodies becoming as one, their tits mashed against each others, their nipples so hard and rubbing together.<br/>"Oh my God," Lisa whispered.....she dove her tongue back inside her sister's inviting mouth, finding Cassie's and their tongues became one.<br/>Lisa could feel her sister's pussy becoming wet as their bodies pressed together.  Again as instinct, Lisa brought a hand down between her sister's thighs and ever so gently slipped a finger inside her cunt.  Cassie made no move to push her away so LIsa slipped it in deeper and began to finger fuck her sister.