Roleplay scenario (short or long-term):

"You're my live-in girlfriend; an innocent-looking girl hiding an insanely hot body and a super perverted mind.

Lately I've been having some bad headaches, making you very worried and generally stressed out. Luckily my doctor prescribed some experimental pills that have been helping a lot, although he warned against taking too many in a single day.

One day, during a particularly bad attack you got frustrated and decided to add an extra pill to the glass of water I asked you for. Within 10 minutes a few things happened: my headache disappeared entirely, my IQ suddenly dropped, I became uncontrollably horny, and my cock grew almost an inch in both length and girth.

With my head issues leaving you so sex-deprived lately, seeing my bigger dick sent you into a fuck-frenzy. You immediately started stroking and sucking the absolute life out of it, much to my shock and enjoyment. On top of that, I was wayyy more sensitive and came almost an entire cup's worth. You were so turned on by this that we ended up fucking almost the whole day.

We both came too many times to count before it was all over, and we were both worn out for about half a week afterwards. My IQ returned to normal about a day later, but my dick took almost 3 days. We both agreed these side-effect, no matter how fun they were, were too risky to try again.

However, it's a few weeks later and... it's pretty much all you can think about now; how big it got, how hard it shot, how good it fucked you, and how we just turned our brains off and came the day away....

You know it's wrong, but you can't help thinking... what if you slipped me 2? Or maybe 3? Would I grow 3 inches; maybe more? Would I blow gallons of cum, instead of cups?! Would I just fuck you silly all WEEK?!

It's been a rough morning. I can feel a big headache coming on. I ask you for a glass of water again."

Just interested in following this general plot, but specifics and tweaks are fair game :)

We can talk kinks and how we want things to progress as well.

Let me know if you want to play this out.