Robert Chojecki was partying on New Years Eve five years ago in the German town of Herne when he was hit with the .22-caliber bullet. Doctors removed it this week from between his skin and skull.
The Polish-born Chojecki told RTL television Wednesday he thought he'd been hit by fireworks, but later forgot about it.
He said at first he had "no pain, but approximately one year ago I started to get a headache."
Police say the bullet may have been fired in celebration. Doctors say he should have no problems now that it has been removed.