Get ontop of her but don't put it in,
From Create Your Own Story
You quickly position yourself so that your arms are either side of her head and that your legs are inbetween hers, which are currently spread, so that your crouch is right above her wet pussy, and your tip is mere millimetres away. Lizzy opens her eyes to feel your hot breath on her face, in shock she freezes, then
"Alex," she whispers "what are you....." she pauses as she feel rock hard tip rub against her pussy lips
"I came to wish you a happy birthday, and give you a small gift" you say teasing, thrusting your hips closer so to rub the now soaking pussy lips further up your cock, to which she lets out a small moan
You lean closer to her ear and whisper "Unless of course you don't want my present"
"But...were...we can't" as she says this you take one finger and run it from her lip down her bony chin, down her skinny neck, inbetween her small breasts, across her belly button and do to her clit, where you slowly rub it and say
"Why not? No ones saying we can't, and you clearly have thought about it" you say signalling at her phone with the naked picture of you
"What about the...UUUUHH" she moans as your finger slips in and out "everyone else?" she is barely able to ask this as her body begins to quiver, and at this point your not sure how long you resist, so you your hand to guide in the tip but that's all, and say.
"That's part of the fun, you'll just have to be quiet" shes smiling now, accepting this is what she wants, and nods. You can tell she's a virgin, normally you would have done a bit of tongue stuff to prepare her but you can't hold on, so you push in slowly, and she begins to moan and bite her lip, as her pussy stretches, and cleches tightly around your cock and you take your sister virginity, but after 4 inches she begins to grunt in pain,
"wait, Wait, I... I don't know if I can take it, your to big"
ignore her and slowly push in more
decide its better to get the pain over and done with and slam forwards