United States Marine Corps

===Unofficial traditions and customs===
[[File:Teufel Hunden US Marines recruiting poster.jpg|thumb|upright|A recruiting poster making use of the "Teufel Hunden"{{sic}} nickname|alt=cartoon of a bulldog wearing a Marine helmet chasing a dachshund wearing a German helmet, the poster reads "Teufelhunden: German nickname for U.S. Marines. Devil Dog recruiting station, 628 South State Street"]]

Marines have several generic nicknames:
* ''[[Devil Dog]]:'' German soldiers during the First World War said that at [[Battle of Belleau Wood|Belleau Wood]] the marines were so vicious that the German infantrymen called them Teufel Hunden – 'devil dogs'.<ref>{{cite book|title=U.S. Marine Guidebook |page=37 |publisher=United states Marine Corps|year=2010|chapter=Marine Corps History, Customs, and Courtesies|isbn=978-1-60239-941-9 |quote=Marines fought like teufel hunden, legendary wild, devil dogs that at one time roamed the forests of northern Germany}}</ref><ref>{{cite book|title=Walking Point: American Narratives of Vietnam |chapter-url=https://archive.org/details/walkingpointamer0000myer |chapter-url-access=registration |last=Myers|first=Thomas|page=[https://archive.org/details/walkingpointamer0000myer/page/114 114] |publisher=Oxford University Press, USA|year=1988|chapter=Hearts of Darkness|isbn=978-0-19-505351-7 |quote=He reminds his charges that "at Belleau Wood the Marines were so vicious that the German infantrymen called them Teufel-Hunden – 'devil dogs'}}</ref><ref>{{cite book|title=To Lead by the Unknowing, to Do the Unthinkable|page= 5|first=Michael|last= Waseleski|year=2009|quote=the 5th and 6th Marine Regiments earned the nickname of "Teufel Hunden" (devil dog) by the Germans in World War I during the 1918 Château-Thierry campaign near the French village of Bouresches, the Battle of Belleau Wood|isbn=978-1-4389-5676-3|publisher=AuthorHouse}}</ref><ref>{{Cite web|url=https://www.6thmarines.marines.mil/Units/1st-Battalion/History/|title=6th Marine Regiment > Units > 1st Battalion > History|website=www.6thmarines.marines.mil|access-date=20 May 2019|archive-date=4 August 2019|archive-url=https://web.archive.org/web/20190804164709/https://www.6thmarines.marines.mil/Units/1st-Battalion/History/|url-status=live}}</ref>
* ''Gyrene:'' commonly used between fellow marines.<ref>{{cite book|title=FUBAR F***ed Up Beyond All Recognition: Soldier Slang of World War II |last=Rottman|first=Gordon |page=49|publisher=Osprey Publishing|year=2011|chapter=GI and Gyrene Jargon US Army and Marine Corps Slang|isbn= 978-1-84908-653-0 |quote=based on Chinese pronunciation of Marine}}</ref>
* ''[[Leatherneck]]:'' refers to a leather collar formerly part of the Marine uniform during the Revolutionary War period.<ref>{{cite book|title=U.S. Marine Guidebook |page=37 |publisher=United states Marine Corps|year=2010|chapter=Marine Corps History, Customs, and Courtesies|isbn=978-1-60239-941-9 |quote=In 1804 the Secretary of the Navy ordered Marines to wear black leather stock collars when on duty}}</ref>
* ''Jarhead'' has several oft-disputed explanations.<ref>{{cite book|title=FUBAR F***ed Up Beyond All Recognition: Soldier Slang of World War II |last=Rottman|first=Gordon |page=51|publisher=Osprey Publishing|year=2011|chapter=GI and Gyrene Jargon US Army and Marine Corps Slang|isbn= 978-1-84908-653-0 |quote=Most likely it was the pillbox cap and high stiff collar making a Marine appear similar to a Mason jar}}</ref>
* ''[[Crayon-eater]]:'' A self-deprecating term originating in the 2010s, playing off of a stereotype of Marines as unintelligent.<ref>{{cite news |last1=Hauptman |first1=Max |date=5 January 2023 |title=When did Marines really start eating crayons: An investigation |work=[[Task & Purpose]] |url=https://taskandpurpose.com/culture/marines-eat-crayons-joke-history/ |access-date=19 August 2023}}</ref><ref>{{cite news |last1=Snow |first1=Shawn |title=Hey, crayon eaters, these M27 rifles are built to be 'Marine proof' Heckler & Koch says in viral post |url=https://www.militarytimes.com/newsletters/good-news-report/2019/02/21/hey-crayon-eaters-these-m27-rifles-are-built-to-be-marine-proof-heckler-koch-says-in-viral-post/ |access-date=20 August 2023 |work=[[Military Times]] |date=21 February 2019 |language=en}}</ref>

Some other unofficial traditions include mottos and exclamations:
* ''[[Oorah]]'' is common among marines, being similar in function and purpose to the Army, Air Force, and Space Force's [[hooah]] and the Navy's [[hooyah]] cries. Many possible [[Etymology|etymologies]] have been offered for the term.<ref>{{cite web
 |last=Hiresman III
 |first=LCpl. Paul W
 |title=The meaning of 'Oorah' traced back to its roots
 |work=Marine Corps News
 |publisher=United States Marine Corps
 |url=http://www.usmc.mil/marinelink/mcn2000.nsf/0/5e9ec5069a2612df85256fea0055d070?OpenDocument&Highlight=2,Oorah
 |archive-url=https://web.archive.org/web/20071224075640/http://www.usmc.mil/marinelink/mcn2000.nsf/0/5e9ec5069a2612df85256fea0055d070?OpenDocument&Highlight=2%2COorah
 |archive-date=24 December 2007
|url-status=dead
}}</ref>
* ''[[Semper fidelis|Semper Fi]]'' is a common greeting among serving and veteran marines.
* ''Improvise, Adapt and Overcome'' has become an adopted mantra in many units.<ref>{{cite book|title=The Marine Corps Way: Using Maneuver Warfare to Lead a Winning Organization |last=Santamaria|first=Jason A.|last2= Martino|first2= Vincent |last3= Clemons|first3=Eric K. |page=149|publisher=McGraw-Hill Professional|year=2005|isbn= 978-0-07-145883-2 |quote=Long before Hollywood popularized it, Marines used the phrase to reflect their preference for being a fluid, loosely reined force that could spontaneously react to rapidly changing situations, rather than a rigid outfit that moved in a specific direction with a precise plan.}}</ref>