Penises are often curved to the right, to the left, up, or down. A lot of people think it is due to masturbating with one hand, but it isn't.
When erect, the penis fills with blood. You can kind of picture it like the penis is filled with balloons. Those balloons fill up with blood creating an erection. Not all of those balloons are the exact same length, however. If the balloon on one side of the penis is longer than the balloon on the other, then you will get a curved penis. No big deal and nothing to worry about unless it is causing pain.
For more information:
"It is nothing to worry about unless is causes pain during erection or sexual activity. It is normal for a man's penis to curve slightly as they get older. In fact some women say they prefer a curved penis because it gives them greater sexual enjoyment.
Just a small note here, the size of your penis or its curve was not influenced by your masturbation activity. All the changes in your body resulted from the growing process associated with puberty."
http://www.teenhealthfx.com/answers/Sexual
ity/933.html
"Penises come in all shapes and sizes, and are curved or straight regardless of masturbation or other sex play."
http://www.teenwire.com/ask/2006/as-200611
10p1380-penis.php
