Boobs! They are awesome and weird. You probably feel like you know everything about yours since they're, you know, on your body, but you'd be surprised — there are some seriously crazy boob facts. Behold.

1. A lot goes into the anatomy of a breast . Female breasts are made of fat, nerves, veins, arteries, breast tissue, and connective tissue.

2. There are eight different kinds of nipples . There's flat, "normal," puffy, inverted, and
more.

3. Six percent of people have an extra nipple . Not that common, but not totally uncommon.

4. Nipplegasms are a thing . Oxytocin is released when nipples are stimulated, which is what causes vaginal orgasms.

5. The world's largest bra size is 102ZZZ . As seen on TLC's Strange Sex .

6. Your left is probably bigger than your right. Even if you can't tell, your left boob is probably slightly bigger than your right, which is the norm for most women . Even Jennifer Lawrence admits her boobs are uneven!

7. Nipple hair is normal . If you have it, you're not alone, and it's nothing to worry about.

8. One in eight women will eventually be diagnosed with breast cancer. There are 10 things every woman can do to help prevent it.

9. Your boobs typically grow for two to four more years after you get your first period. Your mosquito bites really did grow, even when you thought they wouldn't.

10. The size changes every month. You're not imagining a fuller bra. Your hormones change during your period and ovulation, which can cause bigger (and achey) breasts.

11. Smoking cigarettes can cause sagging. Yikes! A University of Kentucky study found that "smoking breaks down a protein in the skin called elastin, which gives youthful skin its elastic appearance and supports the breast."

12. The average bra size in the US is 34DD. Thirty years ago, it was 34B, but it's grown because of "better education on bra fit, breast augmentation, and obesity."

13. Nipples can get darker during pregnancy. Thanks to, again, hormones .

14. Almost five percent of American women have fake boobs. Also, the number of implants created since 1997 could fill an Olympic-size swimming pool. Weird visual, right?

15. Men have nipples because all humans start out as a generic embryo. In the earliest stages of development, embryos follow a "female blueprint ."

16. There's a name for the small bumps on your areola. They're called Montgomery glands, and they produce a "natural oil that cleans, lubricates, and protects the nipple during pregnancy and breastfeeding."

17. Every nipple has 15 to 20 openings for breast milk to come out of. Whoa. These openings are called lobes, and each lobe has 20 to 40 lobules, which have milk ducts attached to them.

18. The nipple and areola are heavily pigmented , which is why they are darker than the rest of the breast.

19. Sleeping facedown can affect the shape over time. Sad but true .

20. Nothing makes your boobs happier than taking off your bra at the end of a long day. According to a scientific survey of thousands of boobs, this is 100 percent true.