My sister's huge tits are hiding a secret!

My dad just got remarried and let me just say I wish he had remained single. I mean his new wife isn't bad. Shes nice. Kinda boring but nice. But unfortunately she wasn't the only person that came with this deal. Thats right. I have a freakin new sister too. Aint that great -_-. Everybody thinks my sister is such a good girl. Cuz she's smiley and pretty. And yea she has really big tits. They're massive. And she makes sure to show them off in everything she wears. They're so jiggly. They bounce all the time whenever she moves. But thats not the point! The point is I know the truth. Shes fooling everybody but me. She's not a good girl. She doesnt have a good bone in her body. She's very, very bad. I've seen her be mean to other students at school. I've seen her talk bad about people she is supposed to be friends with. I've seen her lie to her moms face. All with a smile. There's something wrong with her.