You should be happy with what you have.
However if you really feel the need to increase your penis size,then you should try out these :
Here are four good natural penis enhancement techniques I recommend for rookies. Done properly and consistently, they should add close to an inch or two to your penis in six weeks.
1. Penis stretches. This one is very simple. Just take your flaccid penis and stretch it as far out in front of your body as it will go. Do it gently and gradually and hold it there for thirty seconds. Rest ten seconds between sets and repeat this at least ten times.
2. Jelqing. This is another great technique for rookies. Get your penis halfway erect, apply lubrication, and grip it tightly at the base with the thumb and forefinger of one hand. Slowly slide that hand up the shaft toward the tip, pushing as much blood into your penis as possible. When you reach the tip, immediately grip the base the same way using the other hand and repeat. Do this nonstop for ten minutes.
3. Ulis. This is a great exercise to increase girth. It is also very easy and does not take much time. Achieve a full erection and grip the base of your penis the same way you would if you were jelqing. Squeeze as hard as you can without causing discomfort. Your penis shaft should swell and your penis head should get big and shiny. Hold for ten seconds and rest for ten seconds. Repeat this three or four times.
Do this routine every other day and make sure you warm your penis up before each workout by wrapping it in a hot washcloth for five minutes.
4. A larger penis can be achieved with the use of penis enhancers. There are many forms of penis enhancement products such as pills, patches and topical oils. However, one unique natural product that can produce significant results and makes use of the body’s natural abilities comes in the form of a liquid called super-vir http://www.super-vir.com
Always remember, if you are not satisfied with what you were born with, it is never too late to do something about it!

Unfortunately, there is nothing in any pill or potion that will increase the size of your penis.
However, you can make your penis bigger using natural methods that don’t require any pills or anything other than your hands.
Here is a good site that reviews some of the natural programs available online:http://www.MakeYourDickGrow.com
Good luck!

Why would you want to increase it,
Just as a caution. Some pills like that can actually damage your penis when trying to extend it.
So don’t come crying back to Yahoo! Answers when you say you can’t ejaculate anymore…