I'm not sure exactly what you mean but it's probably your vas deferens. That's the tube that carries sperm cells from your testicles up to your penis. Here's how to tell.
After a hot shower (when they're hanging down more than usual), using your thumb and index finger, gently pinch the skin of your sac (scrotum) between your fingers about halfway between your testicle and your body. Keep rolling and pinching until you feel something like a piece of spaghetti that's not all the way cooked. That's your vas deferens. This is what they cut in a vasectomy to prevent sperm from getting into the ejaculation.
And, as long as you're down there, every guy should examine his testicles for lumps at least once a month. Use the same procedure I described above only roll each testicle around between your fingers. The prime age for testicular cancer is 15-30 and doing this every month will let you know what they normally feel like so you can tell if there are any hard lumps which need to be checked by a doctor. (Just like women do self-breast exams every month).
If that's not what you're talking about write back and we'll try to figure it out.
wrapped around your ball strings????