Tell her the truth

"W-we were up to no good" you offer meekly.

"I'd worked out that much! Now what happened between you two? Hehe, does my little sister have a new boyslut?" giggled Amy.

You frowned at her last comment, provoking a big smile from Amy. You were incredibly uncomfortable with this situation, but thought it better to tell her the truth and get it out of the way rather than try to hold off her questions any longer. One look at Amy made it obvious that you weren't going to win a battle of will or of strength with her, so it was best to do as she told you as long as you were alone with her.

As you tell her what happened, her smile grows continuously wider until it's like a Cheshire cat, and at the end she bursts out laughing, bent over in two, and doesn't seem to stop for at least a minute.

"Hahahah! Oh God, that's ridiculous! But it sounds like something that would happen with Ashley; she's such a ditz! And you really say you couldn't make it stop? I'm not sure about that".

You feel humiliated and were getting rather peeved by this point, but you bite your tongue and simply shake your head at her question.

"I don't believe that for one second. I bet you really enjoyed it. You look like the kind of boy who lets any girl have her way with him and loves a big slice of sausage. Size runs in our family, by the way..."

"Oh, really?" You reply, trying to sound polite but uninterested. Then you realise your error: that rhetorical question was probably going to get a very concrete answer.

"Of course! I saw you staring, you little perv. And is that a tiny tent in your pants? Don't pretend you don't like what you see. Why don't you come and get a closer look?"

Before you can refuse, she grabs your hand and pulls it to her crotch. She was even stronger than she looks and it was obvious that she could impose her physical will on you; there's nothing you could do to stop her.

As you felt her bulge, you gulp again. It was completely flaccid and curled up in her shorts, but it was obviously huge. Even bigger than Ashley's. Your whole palm doesn't even cover her width. You start blushing and she notices, giving you a wicked look. Even though you know this is a dangerous situation, you find yourself giving it a squeeze and exploring it with your hand.

"You like that, don't you, slut?"

Realising what just happened, you say no and try to pull away, but she still has a good grip on you and your hand remains locked against her huge girlcock. This time, she pulls you down to her knees in front of her, so you're at face-level with her bulge.

"Yeah, you love it" she says, and you don't even try to resist any more.

Amy looks down at you right in the eye, knowing that she's won, then slowly unzips her shorts, never breaking eye contact. Her cock flops out, and it's sweaty, musky and absolutely huge. She smiles, and you stand there, your mouth wide open and you hand still on her now naked cock.

"Ashley takes ages in the bathroom. We have plenty of time on our own. Just you and me."

You know exactly what Amy is getting at.