This gives a whole new meaning to the word "boner."

Urology Case Reports recently published a report of a 63-year-old man's penis quite literally turning into bone: a rare disease known as penile ossification.

The gentleman had apparently fallen while walking with his cane, and went to the hospital to get checked out. When doctors took x-rays of his pelvic region (since he landed on his behind), they noticed the presence of ossification—aka, bone tissue formation—in his penile shaft. The report notes that there was "extensive, plaque-like calcification along the expected distribution of the penis,” and its authors now suspect that his entire penis may slowly turn into one, large bone.

What is penile ossification?

Penile ossification is an extremely rare condition, with fewer than 40 documented cases. Often, it's associated with Peyronie's Disease (PD), which is caused by scar tissue, called plaque, that forms inside the penis. PD can lead to erectile dysfunction, along with penile pain.

The man from the study didn't present with any other penile symptoms besides a mild report of penile pain. He didn't have swelling, discharge, or lesions, which can signal infection.

Alas, the doctors couldn't determine if the root was PD or study the man any further, since he left against doctors' orders. "No laboratory, investigation, historical examination, or follow-up was done," the report said.

In a 2013 review in the Canadian Urological Association Journal, the researchers noted that penile ossification was first described in 1827. In that case, the entire length of the penis had become ossified.

That's why it might be worth it for our friend to head back into the doctor's office before it's too late.