The only effects of masturbating too much are potential irritation/chafing from handling yourself too roughly, and potential difficulty maintaining relationships and/or attending to responsibilities if masturbation becomes an addiction. Anything you've heard about masturbation stunting your growth, causing blindness, hair loss, hair growth, etc. is a myth.
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.