Do nothing

You try not to think about it, but just wait for Riley to finish, or get bored, or something. She keeps pouring it onto you, and eventually, even your cleavage is completely filled, and it begins spill, running down the bottom of your chest, and landing directly on Sarah, who looks up at you, a little annoyed.

Well, it's not like it's your fault, right?

Riley puts down the bottle at last, and begins to rub it into a lather, starting with your arms. Sarah stands up, and whispers something to you.

"I recognized the soap she's using just now. It doesn't do anything strange, until you lather it. Then, it starts to make you more sensitive to pleasure. When you rub it onto your skin, the effect is increased. I've heard of a woman who tried to wash her hands with it, and came just from that. In small amounts, it's actually quite nice, but this? You will probably cum from your tits rubbing on each other, let alone clutching them right that."

"N... no..." you whisper. Sure, your arms feel a little more sensitive than normal, but you aren't going to cum, or even get turned on. At least, that's what you tell yourself. "You're lying."

"If you don't want to believe me, that's your problem. I was just giving you a warning." Your knees shake, as she slips a hand between your legs, and drags two fingers over your slit. She shows them to you, and they're glistening. "If you stay like this, it won't be long until you cum, and once that happens, you won't be able to think about anything but your pleasure. But if you think I'm wrong, you're probably right. Back to washing your legs."

She knelt back down, as she said, but her words whirled in your head. She was probably lying, right? You could just do nothing. But what if she was telling the truth? You could probably tell Anastasia, she might come to your rescue, or you could talk to Riley, and try to bargain with her.