Stop her

You smile as you get a wicked idea and head up to her room. You can hear her moans through the door and become aroused, but you hold back and say, "You can only cum when you hear someone else say 'finish', and that will always cause you to have an intense orgasm."

You wait by her door as her moans increase in frequency. You hear her quietly whisper, "Hmmm, fuck me" and begin to imagine that she is picturing you. You touch yourself lightly through your pants for a moment, giving in to this scene, then listen as her moans intensify.

You listen as Erica nears her peak, and hear her frustrated breath as she can't reach the end but doesn't know why. It turns you on, but thinking quickly and on the fly you add, "The only way you can ever get less horny is by cumming."

You hear her redouble her efforts, but you don't want to be caught so you head back to the couch and wait. Soon enough, you see Erica come out in new clothes, though her face is flushed.

"Doing okay?" you ask as she sits back down.

"Yeah, I'm fine" she replies, "Let's just get back to the game."

Interesting, you think, she wants to play this off until I leave.

"Erica," you say, "when you're horny you can't stop your body from periodically giving in to those feelings and making sounds or movements."

As you go to set up the game to continue playing, you hear Erica stifle a moan and look back to see her rubbing her thighs together while thrusting her hips forwards once.

"Are you sure you're okay? It seems like I turn you on quite a bit more than I suspected" you say, laughing it off.

"I'm okay" she replies, red faced. "Just a little flustered maybe. Sorry."

"No problem, we can finish this if-"

"FUCK!" Erica yells as her pent up orgasm wracks her body, her hands digging into her pants as she humps them desperately. You stare at this hot scene in disbelief, unsure what to do from here.