Black Seed oil is all over Amazon, I’m about to order some. Also try Magnesium Chloride lotion from Life Flo. They make high quality supplements, and magnesium applied topically alone will give you more expansion, and satisfaction, out of your jelq sessions. The skin has a voltage on it and I suspect that with magnesium being an electrolyte that might explain why it seems to increase the feeling of pleasure when using it. It can sting on cuts and scrapes so beware that. Not sure what it would feel like to a girl’s vagina, but if it doesn’t hurt the only other option is enhanced sexual stimulation (every feeling and chemical reaction in the body is transport of electrons, so it would definitely increase some sort of feeling if you ask me)