Eat a Boyish Diet
Some gender-predicting "experts" claim that following a specific diet for a few weeks before conceiving could increase your chances of having a boy. They say that switching your diet changes the pH balance in your body, which some believe contributes to the sex of your baby.
According to this theory, your daily "boy producing" menu should be packed with plenty of salty foods, red meats, eggs, peas, raisins, zucchini, mushrooms, beans, sweet corn, bread, and fish. This diet also recommends you avoid acidic foods in quest of a more alkaline (less acidic) environment for the boy-bearing sperm to thrive. (An alkalizing diet, in fact, doesn't necessarily shun acidic foods. For more, read The pH Diet and Your Fertility.) As with all the other advice dished out in this article, you should take this suggestion with a grain of salt … and an extra dash or two if you're trying for a boy.
Also, a recent study suggests that maintaining higher levels of glucose—which means sustaining a high intake of food throughout the day—will increase your chances of having a little boy. Consume a wide range of nutrients such as pottasium, calcium and vitamins C, E, and B12. Breakfast, is particularly important, so never skip!
Take Your Position
Another popular school of thought says that certain sexual positions can improve your odds of having a boy. In ancient times, beliefs abounded about the positions that would lead to male offspring, such as having intercourse with your heads pointing north or having the would-be mother sleep on the left. Discoveries in science over the centuries have led to somewhat more complex theories about positioning (and a lot else). For one thing, we now know for sure it's the male who determines the sex of a child. The mother always provides an X chromosome in the egg; the father contributes either an X chromosome (yielding XX = girl) or a Y chromosome (yielding XY = boy). Each individual spermatozoa carries either X or Y and the baby's sex depends on which one penetrates the egg most effectively first.
According to Dr. Landrum Shettles, MD, author of deeper penetration during intercourse seems to favor boys.
He explains that a woman's vagina is most acidic near the entrance, and—as mentioned before—some evidence suggests male sperm don't fare well in acidic environments. Shettles says deeper penetration puts sperm closer to the egg, reducing the distance the sperm have to travel through the acidic vagina. This gives faster-swimming Y-chromosome (male) sperm a head start over the X-chromosome (female) sperm. Therefore, he recommends rear-entry intercourse for couples who want a boy. (Do I really have to clarify "rear-entry"? OK, fine … he's talking about "doggy-style," people. There, I wrote it.)

Get the Timing Right
Other medical experts also believe that Y sperm (boys) swim faster than X sperm (girls). However, girl sperm typically are more robust and live longer in the reproductive tract than the boy sperm.
So what does this theory mean to you? In a nutshell, if you're hoping for a boy you should try to abstain from sex for several days before ovulation and then have intercourse as close to ovulation as possible. This increases the likelihood that the boy sperm (the faster swimmers) will beat out the girl sperm to the egg, and not have to survive too long while waiting around for the egg to show up. You'll have to do some very careful calendar watching or take an ovulation test to determine precisely when you're ovulating.
Boxers or Briefs?
Sperm are stored "outside" the body for a reason. They can't tolerate excessive heat and the testicles' independent structure and considerable surface area keep them safe from the elevated core temperatures inside the body. Some people claim that Y-chromosome sperm (boys) are even less tolerant of heat than X-chromosome sperm. So, if you're trying for a boy, ask your mate to wear boxers for a while. This will keep things cool and give his "boys" some breathing room.
A cool bath or an ice pack to the scrotum would take matters further, but it's probably a rare male who would be that keen on producing a son.
Crank up the Coffee-Maker
Based on his research, Dr. Shettles says that you're more likely to conceive a boy if your man drinks a strong cup of caffeinated coffee just before intercourse. Why does this work? Shettles says he's not sure—but if anything, it will give your mate a little extra energy boost for the deed!
The jury's not unanimous on whether caffeine for women trying to get pregnant is such a good idea, so you might want to opt for decaf while he goes high-test.
Down Some Cough Syrup
Some people claim that if a woman takes a dose of cough syrup a couple of hours before intercourse, she's more likely to have a boy. Supporters of this theory say that the medicine works by thinning the cervical mucous (just as it thins respiratory mucous when you have a cough), making conditions more favorable for sperm, especially those fast Y swimmers. The key ingredient that makes this work is guaifenesin, so if you're going that route, look for a product that contains it.

Make It Quick
During my research, I spoke with two different mothers who each have one girl and one boy. They both said pretty much the same thing in so many words: To conceive a boy, you should have unplanned, unromantic intercourse.
"Our son was conceived on my husband's lunch break from work," says Casey in Birmingham. "No soft music, no candles—just a wham-bam, thank you ma'am, and get back to work."
Holly from Atlanta gives similar advice. "If you want a boy, your drunken husband should attack you on the living room floor on a random weeknight," she says, laughing. "You should also have no idea where you are in your monthly cycle. That's how we conceived our son."
"Basically, a boy can be conceived with little time, absolutely zero romance, and the high possibility that you could get caught in the act," Casey puts it simply.
Pay the Big Bucks
If you're absolutely desperate to have a boy, you could try just shelling out $20,000. Scientists have discovered a way to ensure that you'll have a girl or boy through in vitro fertilization—where the egg and sperm first meet in the laboratory, not your body. The procedure is a complex medical one that carries a hefty price tag and that couples generally only opt for when all other avenues to conception have been unsuccessfully attempted.
Many people consider this kind of sex selection to be immoral and unnatural and, indeed, some physicians will not test for the embryo's sex before implanting it. Then again, the moral issue is not a common one so far, as most couples can't afford this much green just to get the baby's nursery painted blue.
Adoption is another route where you can be assured of your child's sex. Barring these last two approaches, all you can do is try, hope that fate (er, make that biology) gives you what you want, and love the result regardless.