Random thought on a mechanic someone might have already thought of and proposed it, but...
Vibrators? Like those tiny egg shaped ones. It could be a comparatively simple way of getting a consensual effect of increasing arousal the same way as parasites do, but with the ability to turn it off. Perhaps with some promiscuity or exhibitionism (and propably awareness) requirement before you can buy them or the possibility of getting them from an NPC, first that comes to mind is Avery or maybe theoretically Robin
Edit: yup, someone proposed it already, albeit a little differently, sorry
