My semen is very thick. You can basically pull it out of my penis, almost like a noodle.

I didn't think anything of it until my girlfriend mentioned that it's unlike the semen of the other males she's been with. I was told to drink a lot of fluids and to ejaculate often, but it hasn't helped at all. I've been tested for AIDS and a few other STDs, and they have all come back negative. Is there something wrong with me, and can I change it?

Of all the various aspects of the male human body, few are as variable from individual to individual as semen. The color, texture, and quantity – not to mention the force of ejaculation – vary greatly. Based on outward appearance we are all amazingly similar: virtually everyone has eyes, ears, a nose, and a mouth in the same place. But semen just doesn't work that way. Your situation is not abnormal, even if it is pretty unusual (there's a difference). It probably has to do with the mixture of ingredients in your semen: Semen is designed to "gel" a little immediately after ejaculation, so that it will be retained within the woman's vagina, improving the chances of egg fertilization. Yours just gels a lot. In any case, it's not due to an STD and should not affect your chances of fathering children. But if you're in doubt, ask a doctor (ideally a urologist) if he has any ideas.