A numbing cream, followed by an injected numbing agent, prevents pain. “Depending on the patient’s goals, a filler is chosen and then injected into the corpus cavernosum of the penis [two columns that contain most of the blood during an erection]. The filler is then worked through the penis, to achieve a uniform increase in length and girth,” says Cedar Grove, New Jersey, physician Dr. Muhammad Mirza in a RealSelf Q&A.
During exercises, the spongy tissues are stretched or expanded to increase their maximum blood capacity. A higher volume of blood leads to the formation of micro-tears in the surrounding smooth muscles. The body will repair these tears and encourage the growth of new cells. It’s the same principle that explains how bodybuilders gain new muscles when working out in the gym.
Stretching with weights. Weights or stretching exercises won't bulk up your penis -- it's not a muscle. But hanging weights off your flaccid penis may stretch it a bit, O'Leary says. The catch is that it requires a freakish degree of dedication. "You might have to wear a weight strapped to your penis eight hours a day for six months," says O'Leary. At the end of it, you could be lucky enough to gain about half an inch. Risks include tearing of the tissue, burst blood vessels, and other problems.