[0ct4via]

Neither of these terms are unique to the US, or the military, or indeed the US military specifically.

FOD = foreign object debris... basically anything loose that can end up somewhere it doesn't and cause Foreign Object Damage - https://en.wikipedia.org/wiki/Foreign_object_damage

EFB = electronic flight bag ... basically using screens/displays (and more recently, the likes of iPads issued to Students / Flight Officers/ Pilots) which carry things like aircraft manuals, checklists, airport procedures, airport and aerodrome diagrams, etc. -- so called because they're designed to replace the "flight bag" that could be filled with over half a dozen (or more)heavy, chunky-as-heck books and binders containing the same information in paper form.

This becomes especially relevant when commercial aviation requires flight deck personnel to carry significant amounts of information like that with them, like train drivers can also have to do (rule books, locomotive / rolling stock manuals, track/depot diagrams, etc.)

Again, not remotely limited to the US military, or to the US or military in general -- these terms are common for those in aviation :)

[0ct4via]

In-cabin FOD can be things like loose pens (or even just pen lids/caps), iPads/books, etc. - which is why there are generally rules (admittedly more in the military, because they like that sort of thing) about ensuring things either meet certain FOD requirements/regulations (i.e. pens with screw-on caps, fitted in specific pen pockets, rather than one with a cap that could slide off, loose in a regular pocket), so ensure they don't end up interfering or blocking controls, etc.

As for outside the aircraft, FOD can cover anything from loose rubber / screws, etc. on the runway that could end up damaging the tires or being taken through the engines, to in-flight FOD risks like bird strikes and volcanic ash - which obviously are also foreign objects that risk damage to the aircraft.