Sisters teasing battle

My sister and I are constantly teasing one another. Recently we hung out and she wore a purple shirt with cut off sleeves. We were sitting on the couch when her boob shifted out of her shirt. She was wearing a green see through mesh bra and her nipple was sticking out like her bra was slightly ripped and it was poking through. I swear she did it on purpose but she left it like that for a few mins before she adjusted. I was drooling basically. We are getting closer and closer. I know she loves to tease and she constantly jokes about her being a slut. She makes me so hard and I never try to hide it from her.