I thought I had heard of the term "cupping" in an archaic medical context, so I did a little looking.
Here's what I read. After reading it, I remembered that what I had seen (in fiction set in the Napoleonic era) was a reference to a "cupping glass." The idea was that you produced heat in a cup of glass or similar material by burning something like alcohol inside it. As soon as the fire stops, you place the opening of the cup on the patient's skin. As the air inside cools, the pressure decreases in accordance with the ideal gas equation, which causes the cup to "stick" to the patient because of the low pressure (partial vacuum) inside. The thinking was that blood would be drawn to the cupped area, and the increased blood supply there might heal something. I'm not sure how the practice would adapt itself to sexual or paraphilic activity. I would think that, mechanically, anything you could do with a cupping glass could be done more easily with a wet-dry shop vac. But I guess the sound of the shop vac might be a little detrimental to the atmosphere of a session.