The picture below is from my last session with Frank, who made me the clip attachments because he's a glutton for punishment.
Looking closely, as I know you want to (but will probably regret), I have electrode pads sticking to either side of his balls, and 25 gauge needles through his scrotal skin. Then, taking the alligator clips that were plugged into my Erostek, I attached them to the needles. He described the pain as "piercing". Well, duh!
Are you horrified? Good. Kind of gives a new meaning to the phrase, "Tingly Naughty Bits".