Telling the Truth About My TENS Unit

So, I had a sore back. No big deal, it wasn't a lifetime thing. It got better in two weeks, but the first week was miserable. I bought a thing at Rite-Aid that was supposed to help. It was a Transcutaneous Electrical Nerve Stimulation unit, better known as a TENS unit. I put it in my pocket, and it had leads running to adhesive pads on my back that gave me a mild electric pulse. It really did reduce the pain. So at work, Hank, my codriver, saw the leads coming out of my pocket. I was embarrassed, but I told him what it was. After the "Geez dude, your back" mild sympathy, we drove on in silence for a few miles. He then kind of meekly asked, "Have you ever played with that thing?" I was like "Whaaa?" So quiet I could barely hear him over the diesel engine, he said, "Yeah, like putting it on other parts of your body?" I kind of knew what he was getting at, and couldn't believe my ears. "Well..." "Come on George, you can tell me." Now, I'm pretty open about my... well, about everything in my life. It wouldn't have been the first time the subject of masturbation came up in the cab of that truck. But the other times, the discussion was very generic. "Well, I did put it on my dick," I admitted after another mile. "Really? What was it like?" "After I got it adjusted right, it was really quite nice." Here's where Hank diverted from anything that might be considered normal: "Hey George, when you're done with it, do you suppose I could borrow that thing?" Here's where I want way off the rails, and I'm glad I did, although when I heard the words come out of my own mouth, I almost freaked out in surprise and embarrassment. "Better yet, I'll show you how it's done." More silent miles, then, again quietly, "I'd like that." I looked over, and sure enough, I could see a bit of a bulge in his pants, not unlike the one in my own pants. Now, I should probably tell you about Hank. He is a beautiful, tall, strong black man. Huge biceps. He's the kind of guy who rips shirts because he just overfills them with muscles. And that's a good thing, because the piano moving business does take some strength. I guess I'm pretty muscular myself, but not like Hank. That particular delivery was 250 miles away, and so the company paid us to stay overnight in a motel.  It took us a bit of hemming and hawing, but finally, we got naked, both with slightly abashed boners as soon as our underwear came off. He teased me about lack of suntan. I teased him back about too much suntan. I broke some new pads out of my pack, and placed one in the top of his asscrack, just above his hairy, but very attractive dark black anus, as his erection flopped in front of me. It's true what they say about black guys. They do have large dicks. Or, at least Hank did. Or maybe it's just an optical illusion due to the dark color.  I placed the other pad right on his frenulum.  I thought it might be best to let him control the device. Too much juice at first will make you practically jump out of your skin. Then I decided that maybe I'd be better at controlling it than him. I turned it up slowly, so at first all he could feel was a slight buzz. Slowly, I turned it up a bit more, as I was enjoying seeing that big old dick jumping with every heartbeat. Suddenly, it started jumping way more, like an inch up and down, and his white sperm flowed out across his black belly. What a sight!  As Hank continued to moan in ecstacy, I quickly shut down the unit, and removed the pads. He jumped a bit as I removed the pad from his dick, being sensitive after such a strong ejaculation.  I thought he might be done. I know how I feel after I cum. But no, he was still in high spirits, and wanted to return the favor. I was all for it, and receied one of the best orgasms of my life. As drivers, our relationship changed after that. My wife and his, may have some idea, or maybe not. He and I often try to get the out of town deliveries where we can stay overnight, whereas we used to do our best to get the rookie drivers to take those.