Not yet

You ask Beth to tell Amanda about her experiences here, to which Beth agrees readily. You don't really care about the answers as it's your cock that's driving now. You go around Beth to look at her ass, pulling out your cock to stroke it.

Amanda's eyes widen but she tries her best to maintain eye contact with Beth. Beth for her part looks once at you and resigns herself to being objectified. Perfect. You see what happens if you grab her ass instead of her chest. Her bubble butt is firm yet soft and aside from a loud sigh, Beth doesn't say anything to stop you. With your free hand you spread her cheeks a little to see her asshole, not normally something you're into, but you feel the desire to see all of Beth's intimate areas.

You can tell Beth is distracted by the way she speaks, shifting uncomfortably, but you also see your sister's nude body. If your hormones weren't in control you'd feel guilty and disgusting but right now, you're really jacking off to your sister. You pick up the pace. Amanda sees you eyeing her body and her face reddens.

You grab Beth's ass and spread it as best as you can, pointing your cock at her asshole and unleashing your load. Most of it lands perfectly in her crack with some splattering all over her ass. She shifts uncomfortably at the feeling. You realize they've stopped talking and Beth is just waiting for you to be done.

"Thanks Beth, you have such a nice ass," you say as you tuck your cock away. You grab her tit as if it's a thank you. You can tell from her face that she'd have preferred none of this happened.

"Yeah...uh, no problem. Anyway I better catch back up to my team," Beth takes off and you watch her go, your cum glistening over her ass and better, in her ass crack.