Forget blue balls ... if you lived in the 18th century, you'd have bigger worries -- like accidentally impregnating yourself.

In 1700, the French Academy of Sciences reviewed the "facts" behind a reported case of male pregnancy. After a young man held himself back during sex, he felt that familiar soreness. But he didn't expect that, a few days later, one of his testicles started to swell. Flash forward six months, his testicle had grown to the size a "turkey's egg" -- which, if you're curious, is pretty darn big.

After months of pain and not being able to button-up his pants, he decided to let the doctors amputate. (OUCH!) Once dissected, the surgeons found a hard, white object floating in liquid.

Some folks thought it was a baby's deformed skull in amniotic fluid, others were pretty sure it was some kind of cancerous growth. But everyone agreed it was freakin' weird.

This is not just a one-off story about pregnant men. It turns out pregnant men are all over the place, if you just know where to look. The 16th-century surgeon Ambroise Paré offers up this image of a man who is "pregnant" with his twin -- a condition that happens when one twin dies really early during the mom's pregnancy and gets absorbed by the remaining brother or sister.

Phantom twins aside, fear of self-impregnation has got to be a better excuse than "But baby, it hurts."