NAFOD (pronounced NAY-fahd) is the United States Navy designation bestowed upon sailors who display an unusually low regard for their own lives. It stands for No Apparent Fear Of Death, and upon demonstrating your disregard, a big red stamp reading NAFOD is stamped in your personnel file.
In my career in the Navy, I've met some sailors- probably hundreds of them- who've done some stupid things, actions which showed a selflessly low level of caution. Frankly, these people are valuable to the "brass": crazy people make good Navy SEALs, nuclear reactor repair technicians, and aircraft carrier landing deck mates.
However, NAFOD is far more than just doing a stupid thing or two- it's doing something egregiously stupid repeatedly. But to give you an idea of how rare the NAFOD stamp is, I've only met one naval aviator who earned it. The best part is that he had earned it twice before they took away his wings and made him a weatherman. His first was for attempting an outside loop in Flight School (performed by diving, rather than climbing first) at 5000 feet, directly overhead of his house to impress the wife. He managed to destroy the wings of the plane with the ground effect, as he pulled out low enough that he blew out windows on cars below. The second time, he made a play for the carrier deck (that is, he attempted an ill advised approach), and got stuck in the wake turbulence from the carrier. He attempted to salvage the approach by diving close to the water, which resulted in an extremely low approach angle. Apparently his back wheels hit the edge of the ramp on the back of the carrier, destroying the struts on the landing gear.