You don't dare her.

You smirk at her. "Right, cause that's just what every guy wants, his sister shaking her ass at him and driving him around half-naked." She giggles and sways her butt back and forth a bit more in response. You shake your head. "Are you just getting weirder all the time?" You laugh. "Go get dressed already. I'm hungry and someone promised me an egg sandwich."

At that she heads up the stairs, "Hmph. You're kind of a party-pooper," she complains as she trudges up the steps. "I guess that's why you don't have a girlfriend, despite having the good looks that run in the family."

You call up the staircase as she hurries into her bedroom. "If you think going through a drive-in in your nightshirt is a party, you're the one who needs to get out more. If I was gonna dare you to do something, it would have to be better than that. You show more skin when you drive to the beach, so it's not like it would even be a big deal for you."

Abbie rushes out of her room. She's put on a pair of cut-off jeans shorts, that just barely cover the bottom curve of her buttocks, and a loose tank top that has a low neckline and doesn't quite reach the waistband of her shorts, giving just a glimpse of her midriff. She was more covered up before she got dressed. "Ooooh." she coos as she jogs down the stairs towards you. "What better idea do you have to dare me?" She asks sounding oddly excited. "Do you want to see more of your sister's skin than my bikini shows, perv?" She chuckles. She stops a few steps from the bottom of the stairs and leans forward, catching herself on your shoulders, so her face is level with yours and very close.

You raise an eyebrow at her. "Yep, you're definitely getting weirder, Abs," you tell her. You wonder why you can't be casual and joke around like this with pretty girls who aren't your sister.

Abbie lowers her face into the side of your neck and inhales. "Did you get a new cologne or body spray or something? You smell good today."

You laugh at that. "The only thing different is I rushed my shower. I probably smell more like me and less like soap."

Her nose is pressed against your shoulder and her arms tighten around your neck. "Fuck!" she says in a low growl. "You need to get the balls to ask a girl out today. There's no way any of them would say no if they get a whiff of you like this."

Now she really is being weird. You start to feel nervous and uncomfortable like you do around other girls.