Hello, You were on high ropes and had a harness on. You had a popping sensation in your left testicle all of a sudden and got bruised. Presently, the bruise is gone. Your symptoms can be indicative of trauma on the testicle due to not tightening your harness sufficiently and getting hurt. You should wear jock strap and proper fitting harness when on high ropes. to prevent injury on testicles. Popping in your testicles may be due to either testicular torsion or rupture of the balls. Bruising after exercise, which is bleeding underneath the skin due to tissue damage and broken blood vessels. Initial treatment consists of rest, ice, compression and elevation. You are suggested to get clinically examined by a urologist. If the bruising is internal, then your doctor may order an ultrasound to locate the source of the bleeding or any testicular torsion. You will be treated accordingly. You may require a few weeks of good scrotal support as well as anti-inflammatory medicine and ice on and off for relief. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician