Doctors in the UK have recorded the first known case of a penis breaking vertically during sex.
The 40-year-old man's member 'buckled against his partner's perineum', or the area between the anus and genitals, before a 3cm tear opened at its base.
Doctors did not say what position he was in, but penis fractures are most commonly triggered by 'doggy style' and 'man on top' positions, they wrote.
There are no bones in the penis, but breaks usually happen when a man's penis slips out of his partner and is suddenly bent, which can cause painful swelling.
Medics who treated the patient, believed to be from York, revealed the tale in a case report in the .
They said that all previously recorded penis fractures had been horizontal.
But in this case it split up the tunica albuginea - the protective layer around the erectile tissue that pumps blood to this area.
Doctor's said no 'popping' sound was heard when the break occurred, which happens when fractures are horizontal.
The arrow points to the 40-year-old's tunica albuginea - the protective layer around the erectile tissue that pump blood to the penis - where there was a three centimetre tear (circled)
The man's member 'buckled against his partner's perineum', or the area between the anus and genitals, before it a 3cm tear opened at its base
But the patient's penis gradually swelled up after the injury.
Six months after treatment for the injury doctors said the man was still able to achieve 'erections of the same quality to those prior to the injury'.
Doctors added there was no long-lasting curving of the penis, or palpable scarring.
The urologists said 88.5 per cent of penis fractures occur during sex, with a 20-year study finding that 'doggy style' and 'man on top' were the most commonly blamed positions.
Other causes of penis breaks include masturbation, sleeping position and taqaandan - the practice of forcibly bending the penis, which is primarily performed in Middle Eastern countries, according to the report.
Men in their 40s are most likely to experience a penis fracture, accounting for ejaculoid results in up to seven in 10 cases.
The British Association of Urological Surgeons recommend operating on fractured penises within 24 hours to reduce the risk of long-term problems like erectile dysfunction.
A penile fracture occurs when the appendage is subject to a sharp, blunt force trauma, which can occur during vigorous intercourse or masturbation.
Since 1924, 1,600 cases have been recorded worldwide - roughly 16 instances per year.
Researchers noted that in 50 per cent of cases, a gruesome cracking sound can be heard.
Four in five male victims lost their erection.
Those who have already been traumatised from breaking their penis are often left with erectile dysfunction problems and a lifetime of painful sex.
Blood flows into corpora cavernosa that runs along the penis and making it hard during an erection.
The trick to stopping penile injuries is to thrust quite shallowly, according to sex expert Tracey Cox.
Holding your partner close to you using a grinding rather than thrusting motion will also reduce the risk, she told MailOnline.