I found the following story from this week's episode of QI (Series J, episode "Just the Job").
I'm not sure of the exact date of invention, but the late Victorians came up with this little beauty:
This is basically an electric jock strap. It was used to help men counter impotence (as well as being a "cure-all" for a number of other issues for both genders) by shocking or stimulating a person's tenders.
The adverts themselves were really hilarious because they used coded language to explain its purpose, like the flexing Chippendale dancer in their advert wouldn't give the whole thing away, anyway.
A typical advert read:
"FOR NERVOUS DISEASES of all kinds in men and women, to reach the nerve centers for the cure of all nervous disorders the Heidelberg Electric Belt stands alone. For weakness in men and women, personal exhaustion bringing back lost strength and power, over brain work, vital , impotency, rheumatism, sciatica, lame back, railroad back, insomnia, melancholia, kidney disorder, Bright's disease, dyspepsia, disorders of the liver, female weakness, poor circulation, weak heart action and almost every known disease and weakness. The constant soothing alternating electric current is ever at work touching the weak spots, building up the system, stimulating the circulation. ALL THAT ELECTRICITY WILL DO FOR YOU WILL BE RECEIVED through the use of our electric belt."
The adverts also gave a 10 days free trial, so buyers might end up with a used one.
This is hardly the only electric sexual aid from the Victorian era. Electricity really came to the forefront of a lot of medical discourse because, still being fairly new, doctors and inventors needed to experiment with it and see if this magical new thing could be used in medicine. They weren't always wrong. Electricity helped with the dubious medical issue of "hysteria" by being used in the invention of what I can only describe as a mechanical bull vibrator (actually called "Vigour's Horse-Action Saddle").