Police said Tuesday that the 35-year-old men was hit by a .22-caliber bullet in the western town of Herne as he was out in the street partying and drunk on New Year's Eve five years ago.
They say the man recalled receiving a blow to the head, but told them he didn't seek medical assistance at the time.
The bullet did not penetrate the skull, and police say the man only went to see a doctor recently when he felt a lump on the back of his head. An X-ray showed an object under his skin, and doctors operated and found the projectile.
Police say it may have been a stray bullet fired by a reveler in celebration.