2 5 Day refers to the 5th day of the second week in the United States Navy's boot camp.
Recruits who have not yet reached 2 5 Day will hear it referenced constantly while hearing little if any details about why it is such a dreaded day. Recruits beyond 2 5 Day are more than happy to scare newer recruits in the manner of doing unto others as was done unto them, they are unlikely to share the details.
They make you cry... like a baby.
Progress through boot camp is marked by the recruits with two numbers, the first referring to the number of weeks they've been there and the second to the number of the days in that week. For instance, work-week begins on 6 1 Day and ends on 6 5 Day.
2 5 Day serves a very important function in boot camp. Eighty young strangers either come together as a cohesive unit or fragment into stoic, but incomplete, cliques.
The day begins like any other with reveille, 'shit shower and shave', breakfast and some light PT (physical training). Upon return to the barracks the recruits are given some free time with which to straighten up their personal areas, locker and bunk and such, and generally stoke each other's fears about what is to happen.
After a short interval, the CC (Company Commander) will come in, have everyone get on the line, stand at attention, and here 2 5 Day really begins.
In rush six to eight other CCs, all of them complete strangers to the recruits. These CCs come in fast and loud. They divide the recruits up into even numbered groups and begin giving them the hardest time possible. It is complete chaos in a matter of seconds.
We'll examine one small corner of the room first. One CC is facing 10 recruits, standing at attention. He is shouting at them that they must pay very close attention to every word he says. He will 'inspect' their lockers and bunks. No matter what condition a recruit's area is in, fault will be found. The CC will punish his recruits hard, as a group and individually. He will do his best to frighten them and tire them.
When you factor back in the other 70 recruits and the other 7 CCs shouting at the top of their lungs you may get an idea about how difficult and chaotic this is designed to be. Standing on the line, 'your' CC may be facing away from you while asking you a direct question. He knows that you can't hear him over the din, that is the idea. You will be punished for failing to answer the question. Upon completing the 20 pushups you were ordered to do for failure to fold your socks properly you will be informed that you did three of the pushups incorrectly and so must do the entire 20 over again.
After several hours of this chaos, many mattresses flipped, many lockers thrown across the room, the second phase begins. Just as suddenly as the CCs rushed in, they will melt away. Left in their wake are 80 recruits completely wrung out. They are soaked in sweat from head to toe, they are more exhausted than they have ever been in their lives. Having only been here two weeks they are seriously reconsidering the wisdom of their choice to enlist.
It is at this point that the recruits hear the opening chords to Lee Greenwood's "God Bless the USA" (more commonly referred to as 'Proud to Be an American'). In comes another stranger to the recruits. He is smaller than the other CCs, he moves slowly and quietly. He gestures that the recruits should relax and gather around him. For the duration of the song the only thing that can be heard is the huffing and puffing of those still trying to catch their breath. Near the end of the song or directly after it is over this new CC begins to speak, softly.
He is the good cop to the other CCs bad cop. He will talk very softly, a trick used by psychologists and mothers around the world to quiet the insane or hysterical. One must stop crying in order to hear.
He will tell them he understands, that he knows homesickness and feels their weariness with them. He assures them that very soon they will be allowed to call home for the first time. He slowly moves into a prepared speech about unity and fellowship in the armed forces. Somewhere in the dialogue an American flag is brought out and handed to the clumped recruits. They are all encouraged to get a hand on it. This is where the tears come in.
We have a great big clump of hushed, 18 year old recruits. They are mentally and physically exhausted. They are away from home for the first time. They have just finished listening to Lee Greenwood and are now caressing an American flag as the only authority figure in sight assures them that the men around them are all they have to rely on, and oh yeah, its okay to cry if you want.
To return to the personally specific, when I and my company went through 2 5 Day we made it. If I had to guess I'd say most companies make it, though I know not all do. We had a recruit rolled into our company from a company ahead of us. He related to me in some detail his first 2 5 Day and how his company did not bond, how during the song and the holding of the flag they were merely physically exhausted, how they resisted the emotional breakdown. It was understood that this was significant in his being rolled back. His was a problem company. Their failure to come together on this day made the rest of boot camp exceedingly difficult for them.
As to the long term effects, I believe they are nil. This exercise is only one of many designed to create trust and foster a close-knit feeling of community. In the Navy, no more so than in the other branches of the Armed Forces, it is paramount that you work together with those around you - that you work as a team in a trusting environment. Your life, very literally, can depend on those around you. 2 5 Day is one way of creating that environment, of giving the recruits an idea of what is going to be expected of them throughout the rest of their career.
For reference, I attended bootcamp in Orlando, Florida in the summer of 1995. Given the desired outcome, almost any exercise can be designed to accomplish the same goal.