Finding your own sister on a live stream cam site was initially very scary, but then... you found that your cock was actually harder than it has ever been before. So you just have to use this to your advantage. Knowing that she's actual a real bitch, she won't take it well when you tell her you've seen her online. All you want is to see her naked body in person! And now you can... because your parents would be very disappointed if they found out, hmmm