hi im 20 and my penis is about 5in hard. what can i do to make it bigger? and is those penis pills real?

Your penis could still be growing. The pills do not work. Learn to give great oral sex and how to use your penis well and size will not matter. 5 inches is normal. It is small normal, but normal. Nothing you can't do with 5 inches that another guy can do with 6 or 7. Most guys who say they have over 7.5 are lying.
Learn to love what you have and the person who loves you will too.

Good advice.
Like Susan says, Girls would rather be with a "Small" experienced guy, than a "Big" Dumb one.

I'm another that will vouch for size not being the most important factor in a good (or fabulous!) lover!! Have you considered how difficult it is for a partner to perform oral on an overly large or even big/normal erection? You may even find a partner far more willing to experiment- perhaps anal?
I'm not sure how men measure, but I can almost promise most of them add an inch or two into their estimation, and unless you'all run around the locker room "hard", there's really no way to tell what another guy's flacid penis will grow to be when hard. Enjoy what you have- if you can help your partner reach orgasm by almost any means, she'll think you're the best no matter what size you are and word of what a wonderful guy you are will get around!