[Abbreviation for ‘Finger of Death’, originally a spell-name from fantasy gaming] To terminate with extreme prejudice and with no regard for other people. From MUDs where the wizard command ‘FOD <player>’ results in the immediate and total death of <player>, usually as punishment for obnoxious behavior. This usage migrated to other circumstances, such as “I'm going to fod the process that is burning all the cycles.”
In aviation, FOD means Foreign Object Damage, e.g., what happens when a jet engine sucks up a rock on the runway or a bird in flight. Finger of Death is a distressingly apt description of what this generally does to the engine.