It is like saying "welcome aboard" to a new guy, or "no shit, it sucks here"! Can also mean we have to put up with an asshole SNCO or an Annapolis graduate or new lieutenants? Can also be a term of endearment between brother Marines meaning, "hey we are all in this together and will get through it"! Can also be like saying when your under fire, "calm down, don't panic this is war". Still it can be as simple as "oh fuck, another fucking inspection", having a shitty CO, living in a rundown barracks, being in a total shit-hole, or doing the Army's job for them as usual. But, its between Marines and Marines only!
Another could be...............after having worked on a helicopter(maintenance) all night, you have to do PFT at 0600 hrs.
Or another could be........those fucking niggers/splibs at supply won't give me the parts I need to fix the bird?