AN ex-convict feared he had broken his 4-5 during sex after he woke up to find it hugely swollen.

But instead, the 41-year-old man had just knocked a domino fragment that he shoved into his 4-5 while in jail two years earlier.

The former drug addict reportedly carved a piece of domino into an arrow shape and inserted it between his skin and penile muscle to “enhance sexual stimulation”.

Doctors in New York, who treated him, assumed he had snapped his 4-5 because of how swollen it was.

Yet the unidentified man suffered neither pain during sex nor heard the dreaded “pop” sound – the hallmark sign of the grisly injury.

Doctors felt a 1,5cm-long object buried in his 4-5, which prompted him to confess about what the lump actually was.

According to the Daily Mail, he revealed that during his time in prison, he used a “pencil” to push the domino piece into his penis.

Doctors noted that his 4-5 was severely infected and bruised.

The doctors who published the story in the Urology Case Reports journal revealed that he was given antibiotics to fight off his infection.