If you think there's more important terms that could prove useful in the server chat, go ahead and post them, I will add as I see them!
A
Aye aye - Used as a way to acknowledge a order. "Soldier, do this!" "Aye aye, sir!"
ASSHOLES AND ELBOWS - in a hurry; quickly. This was used in the Aliens movie. E.g. :h YOU HEARD THE MAN, ASSHOLES AND ELBOWS! LET'S GO!
Acting Jack - either assistant Drill Instructor, or acting Corporal. If I am correct, it can be used for when the SL steps down, forcibly or not, and another member of the squad assumes his role. E.g. Alright boys, SL was just devoured by an Alien or something, I'm the Acting Jack now.
A.C.E Report - Acronym for Ammunition, Casualty and Equipment report. Squad leads who asks said report expects a quick answer from their subordinates. A "Good" or "Bad" is a typical reply.
All Hands - Entire ship's crew, in this case the Sulaco's crew.
AO/Area of Operations - the geographical region whereas a unit or platoon has to control and carry out a mission. In CM, it would be the playable area of the Planet (Alpha), or the Nostromo.
Ass Pack - Can be used as a reference to the marine belt.
Ate Up - A person who is lazy, unsatisfactory, irresponsible and unaware of what's going on. E.g. Look at the rookie, he's Ate Up.
AWOL: Absence Without Leave, this means Desertion, this marine ran away like a coward, he didn't wanted to follow orders and tried to stay away from the fight or tried to mutiny against his superiors. E.G: SL: "Alpha, we strike at the caves", Marine: "No" *runs away*
B
Brass - Regards the "higher ups" or the personnel in command. "Looks like the Brass wasn't thinking on this one."
Boot - Offensive term used for rookies, new marines fresh out of boot camp. E.g. Looks like we got a lot of Boots in briefing today.
Bird - Unknown aircraft/Aircraft/Ship
Beans, Bullets and Bandages - Rations, Ammunition, and Medical Care
Beer-thirty - Time of dismissal of the day's duties, this is a reference to that time because a marine is then free to drink Alcohol.
Belay - To cancel an order or stop
Big Green Weenie - An expression used for when a soldier has been unjustly fucked over by the marine system. E.g. Commander won't send the drop ship. We're all Big Green Weenies.
Brig Rat - A regular offender; marine who has served a lot of brig time
Brown Bars - Typically a newly recruited second lieutenant. Marines under the command of said second lieutenant refer him/her as "brown bars" when performance is unsatisfactory. Insult Acting Jacks with this!
Barney-Style - "Let's break it down, Barney Style". Some Marines need some help in understanding how to complete a task. E.g. SL, I don't know how to do this. Can you break it down to me Barney Style?
C
Check Your Fire — order to stop firng due to a possible error or mistarget. E.g. *Player gets shot by some random noob with a gun* say CHECK YOUR FIRE!
civvies — civilian clothing E.g. :h Sir we just found someone alive, he's wearing civvies. Must be a survivor.
COB — Close Of Business, the end of working hours; or Close Order Battle, a synonym for CQB. See also beer-thirty. E.g. I can't wait for the Close of Business.
clusterfuck — chaotic and messy situation; multiple mistakes or problems happening in rapid succession. See also goat rope. Almost any CM round ever, use this to describe what you're going through.
cover — helmet. E.g. "Dude a facehugger just jumped me, took my cover off!"
CQB or CQC — Close Quarters Battle/Combat, combat within a confined space, such as urban warfare. See also MOUT. Heading into the caves? Expect some CQC.
D
death by PowerPoint — overly long and boring brief, from the tendency of briefers to over-use the presentation software. Use this to mock the Commander at briefings. I'm not responsible for any ass kicking you may endure.
defecation hits the oscillation — polite version of the expression "shit hits the fan"
Devil Dog or Devil — nickname for Marines, a name earned by Marines fighting at the Battle of Belleau Wood; from the German word "teufelhunden". Go ahead and call yourself or your squad mates this if you're feeling funky.
devil dogging — correcting another Marine's minor deficiency, often in public with implied humiliation. There's a noob marine doing something retarded? You should devil dog him
dickskinner or dickbeater — human hand. E.g. :h OH GOD THE SL JUST GOT HIS DICKBEATER CUT OFF BY AN ALIEN!
dope — information, or sight settings and/or wind corrections for a rifle under given conditions. If you like to play the Sniper this is for you. Or alternatively, say :h Everything is dead, lots of blood and strange resin. We need some dope about this.
drop a dime — to reveal incriminating information about a person. A marine is doing something stupid like disobeying his SL's orders. E.g. :h Hey jackass, wait until we get back to the Sulaco, I'm dropping the dime on you.
E
eightball — worthless, troublesome individual. Use this to describe noob marines
EPD — Extra Punitive Duties, punishment assigned where the individual is required to perform cleaning duties after working hours (on his or her liberty time).
F
fat-body — overweight recruit or servicemember. Call a marine this if you don't like him.
feather merchant — Marine of slight build, lightweight. Call a marine this if you... don't... like him?
final protective line — the perimeter at which the enemy has begun to overrun friendly troops, signals the commencement of final protective fire in desperate self-defense. Aliens overrunning the last FoB, means a final protective line is in effect.
FNG — Fucking New Guy, derogatory term for a Marine recently graduated recruit training and new to a unit. Call a rookie or a newbie this if you're an asshole.
FUBAR — Fucked/Fouled Up Beyond All Recognition/Repair. If you're playing as a marine expect this to sum up what you're going through perfectly. Or alternatively just look at somebody's corpse and describe him as FUBAR. I love this one, go nuts.
Fire Watch - Guard Duty. You were assigned to protect the FoB? You're on Fire Watch.
G
gagglefuck — group of Marines grouped too closely or in an unorganized fashion; from gaggle, the term for a flock of grounded geese, and clusterfuck, a term for a messy situation. Almost all marine squads end up turning into a gagglefuck.
goat rope — chaotic and messy situation. Goat Rope describes a marine's experience in a round perfectly.
grunt or ground pounder — infantryman.
H
hack — arrest. "That guy is going around punching people, MPs, hack him!"
high and right — losing one's temper or rationality. "OGOD ALIENS EVERYWHERE HELP ME O SHIT" "Hey, you're high and right!"
huss — to give a helping hand. "I got a Predator stalking me, I need a huss!"
I
Iron Mike — nickname bestowed on Marines who score a perfect 300 points on the Physical Fitness Test.
J
jarhead — pejorative term for a Marine, though a marine can call another this. It kinda works like the N word.
K
keyboard jockey — person whose job causes him or her use a computer for a length of time. "He's been promoted to Overwatch. Looks like he'll be a keyboard jockey from here on out"
KIA: Killed in action, a marine with this classification was killed and someone else can confirm it. E.G: a marine is killed on the caves and another marine saw him begin killed.
L
lollygag — dawdle or fool about. A marine strayed from the group, disobeying orders entirely and just going around like a dumbass? He's lollygagging
LZ — Landing Zone, a clearing designated as the place where a helicopter (or other VTOL aircraft) can land.
Leatherneck - military slang term for a member of the United States Marine Corps, or of the British Royal Marines. It is generally believed to originate in the wearing of a leather "stock" or collar around the neck, which kept the posture erect.
M
ma'am — proper method of addressing female officers in particular and all women in general.
MIA: Missed in action, a marine that was on a mission and than lost contact. He may have been killed, captured or deserted; but nobody is really sure. E.G: two marines are walking around, xenos attack but they don't respond and get infected. Another example: Guy goes SSD and nobody ever hears about him.
mike — minute. "Five mikes to extraction!"
moonbeam — flashlight. Your moonbeam is your most precious item when facing Xenomorphs.
motarded — displaying excess motivation, a combination of the terms "moto" and "retarded". If a marine acts like Rambo, says he wants to go solo on all the aliens, please do call him this.
N
Ninja Punch — NJP, or NonJudicial Punishment, a legal proceeding much like a court-martial of much smaller scope. This ALWAYS happens if a marine has done something illegal, seeing as there's no court on CM as of yet. "You're totally getting Ninja Punched when we get back to the Sulaco!"
nut to butt — standing in line extremely close to the person in front. Imagine you're going through the tight and narrow caves of a hive. You'll all be nut to butt.
O
O-dark thirty — very early hours before dawn. See also military time. The custom of saying "oh" instead of zero has diminished, but remains in this expression. You land on the planet, "it's still pretty dark down here, must be O-dark thirty."
Old Man — very informal nickname for the commanding officer, considered an inappropriate term of endearment for use by a junior, thus used in reference but never in address. Call the commander this behind his back and giggle.
Oscar Mike — On the Move. This one must be known amongst CoD fanboys. "ALL OF YOU ARE TO HEAD TOWARDS THE HIVE IMMEDIATELY AND ASSIST!" "ROGER THAT, WE ARE OSCAR MIKE!"
P
piss and punk — solitary confinement on bread and water, which is only authorized aboard ship. "YOU'RE GETTING PISS AND PUNK FOR THIS!"
pop smoke — to leave quickly or hastily. "ALIENS OVERRAN THE FOB! POP SMOKE! POP SMOKE!"
POW: Prisioner of war, this marine was captured and now is held hostage by the enemy. The POW should be treated with respect according to the geneva convention, so no harming human prisoners. However, since most POWs will be marines on the hive or captured aliens this isn't important.
pucker factor — high level of anxiety experienced by those in tight situations. Pucker factor will always be a thing amongst marines battling dozens of vicious, horrible aliens bent on forcefully impregnating them with chestbursting worms.
R
R&R — Rest and Relaxation, authorized absence from a combat area to reduce the effects of combat stress reaction. "Alright you boys had it rough, get back to the Sulaco for some R&R."
REMF — Rear Echelon Mother Fucker, a derision for someone who serves in a non-combatant role. Idk, use this if you've been assigned to FoB and don't like it. "Ah man, Fire Watch? I know we'll just all be some Rear Echelon Motherfuckers.
RHIP — Rank Hath Its Privileges, used as a justification for a personal indulgence. "The SL is a fucking moron..." "Rank Hath Its Privileges."
S
salty language — profanity. Don't use salty language against your Commander, please.
shit bird — habitually unkempt or undisciplined Marine. Insult marines you don't like with this!
shit-brick — useless or ignorant person. Insult marines you don't like with this!
shit-hot — sarcastic reference to an overly arrogant person. Insult marines you don't like with this!
sick bay — infirmary or other medical facility aboard ship, can also refer to aid stations ashore. "He's badly hurt, we gotta get him to the sick bay!"
smokin' and jokin' — when a mass of Marines is acting unproductive. When a bunch of marines are just sitting on the FoB doing nothing, they're smokin' and jokin'.
SNAFU — Situation Normal, All Fucked Up
snot locker — nose. "Keep that up and I'm gonna punch your snot locker in!"
SSDD — Same Shit, Different Day, euphemism denoting frustration with an unchanging situation or boredom. "We're going to the Nostromo/Planet? Ugh... this totally won't be anything dramatic and intense at all, just boring. Same Shit, Different Day.
SITFU - Suck It The Fuck Up. Use this if a marine is screaming his lungs out because he broke a nail. Do NOT use this if a marine got a limb or two sliced off, unless you're an asshole.
Skating - Slacking off, avoiding to do a task. "Yeah, I'm Skating this one."
T
tight-jawed — angry, so named from the human tendency to clench the jaw when angered. "That squad is a bunch of tight-jaws."
tore up — broken, messy, unserviceable. "The computer is pretty tore up."
trooper — soldier, considered an insult to refer to a Marine unless plural.
U
un-ass or un-fuck — to correct a deficiency, usually on a person. "YOU BEST UNFUCK YOURSELF PRIVATE PYLE!"
under way — to depart or to start a process for an objective. "We're to assault the hive? Under way!"
unsat — abbreviation of unsatisfactory. "This is unsat duty."
W
WIA: Wounded in action, this marine is wounded, take him to sulaco.
wilco — Voice procedure term shortened from "Will Comply". "Aye aye sir, wilco."
► Show Spoiler
