I like where this item is going. I am unsure if Dr. Badger would create a product that looks very commercialized though (as described in the item's description), so I would suggest toning that down a bit--the item can still be called by the same name though. Maybe have it labeled as being an experimental mod of some sort?
As far as use, I like that the item's effects can be triggered after using a hip tease. For the "Shake" action, I would recommend lengthening the scene so it is more than just a paragraph, though with a few things in mind: characters who do not have vaginas (as it seems this item was written for complete females), the current location (public, private, hazard, etc.) vs the character's exhibitionism level, and possible considerations to tails (if the character has any). If the item wears out and hasn't been activated, there should also be a dud message to notify the character that the drug has expired.
The overdose scene seems okay, but if the character is to gain any of the potential perks afterward, I would suggest that you include accompanying blurbs with them as well, just so the player knows exactly what perk was gained instead of it being completely random. Example:
You rub your hand over your newly-sized behind. {if high tone: Despite your toned body, your ass feels fat!} Oh, your [pc.buttcheek] has become completely plush and malleable to the touch. You have a feeling that no matter how tight your body is, your bubble-like butt will always remain soft and spongy!
(<b>Perk Gained: Bubble Butt</b> - Ass remains soft regardless of muscle tone.)
I am not too keen on the idea of limiting sex scenes based on the "Hips Don't Lie" perk though. Limiting sex scenes is a lot more complicated and would require editing every option for every single sexual encounter. I would recommend cutting this perk entirely or replacing its effects with a different idea.
All that said, After you've completed your writing, I would highly recommend passing this off to some editors and other writers. I have spotted numerous grammatical, spelling and tense errors in the writing so far, so a few revision passes should help better the quality in that area.
Best of luck on the rest of the writing!