The origin of the term is commonly associated with the Battle of Belleau Wood which took place in France during the First World War. The Germans were shocked at the ferocity of the attacking
U.S. Marines (elements of the 5th and 6th
Marine Regiments) and called them "Teufelhunde" which loosely translates to "Devil
dog". After the battle, the French renamed it "Bois de la Brigade
de Marine" ("Wood of the
Marine Brigade").
1. Commonly used to address another Marine and has no real negative connotations (unless spoken sarcastically, at which point the speaker is likely to spring a rather nasty leak).
2. Used to address a Marine who's name is not known (before nametapes on the utility uniform became standard).