"F.O.D." stands for "Foreign Object Damage".
You may have seen videos of Sailors lined up shoulder to shoulder walking the deck of an aircraft carrier, searching for the tiniest scrap of F.O.D.
Although the typical flight line is too large to do that, Soldiers and Marines are constantly on the lookout for F.O.D. and are reminded that the tiniest scrap of metal can result in expensive and disastrous results on aircraft, and sometimes cause loss of life or limb.
Want to see F.O.D. in action? Take a look...