Hot Summer Job/Be coy, make her beg for it more
"Do what again?" you repeat.
"What you just did," is all she can reply, her fingertips gently kneading at your skin.
"What did I do?" you ask, raising an eyebrow.
Her humping has some hesitation behind it now. She's probably having a hard enough time admitting what she wants to herself, let alone to you.
"You, um... you pushed... up."
"Up how?"
She fidgets a bit, groaning to herself struggling for words she's comfortable with. "I dunno. It felt like... I dunno. I felt 'full' I guess."
"Full? What does that even mean?"
"Riiiiiley..." Bree moans, grinding against you more blatantly and purposely.
"What? I really don't know what you're asking," you insist.
"I dunno, I... I want you to..." She keeps glancing at you then looking away. Finally she lowers her voice and leans a bit closer. "...to push inside of me."
"Oh. Do you mean like this?" you ask with a short thrust.
"Yeah! That!" she exclaims. "Do that again!"
"Why?" You can't help yourself.
"Because." Her exceptionally eloquent argument falling flat, she adds after a moment, "Cuz I want you to."
"But what if I don't want to?"
"Riley!" Your little sis smacks your chest lightly then squeezes her legs repeatedly to draw herself up and down your shaft as much as she can. "Just dooooo it! Do it in me! Please!"
You thrust upwards more forcefully than the last one, but still teasingly compared to a moment ago.
"Again, do it again!"
Another thrust of equal measure is met by a weak gasp from Bree.
"H-harder."
You follow your sister's instructions, bucking into her with more gusto and bottoming out inside her like before.
"Again... again... again... more, more..."
You give her a bit extra on that last one as requested, really burying yourself. She responds with a whimper. Her fingers dig into you as if they were trying to grab the sensations you're inducing in her.