How would you react to an E2 who "smart mouths" you in formation?

I would assign him the most demeaning task I could think of, cleaning the toilets with his bare hands, scrubbing the floor with a toothbrush. Something like that.

I’d kick his ass in front of the platoon. But, that is me. A more disciplined Marine NCO would virtually take Pvt Shitbird apart with commanding rhetoric and an overwhelmingly dominant attitude.

Promote to E-4 mafia

Crushing his soul my be in order. However, is this a first offense? If it is, a heart to heart in the PSG's office with the platoon sergeant and platoon leader is in order. The Soldier needs to understand insubordination and the consequences, and it needs to be on paper. Make sure the kid knows that it's serious and that the counselling has the magic bullet in it. If it isn't . . . Well, time to start crushing souls. I typically start with summarized and work my way up from there. Most joes get it when their time is taken with out the need to go after pay and rank. If they don't . . . That rank and pay is going with more of their time.

How the hell did he make it that far. If he has been in that long and with that attitude he did not just wake up and decide to be an idiot. I was a Marine, in my experience he would not have made E-2. As a corporal and squad leader, at various times when I got a new guy I checked his background and past performance. He didn't just walk out and report in. If by chance he did just get assigned and I wasn't informed until he was standing there his new fire team leader would meet him first. Usually it was the Fire Team Leaders and myself in a meeting. I told them what I wanted done and they told their team. IF for some reason I had to do this as a squad the minute he opened his mouth he would be standing at attention by himself off to the side while I finished. His new fire team leader would assist in addressing his problem and develop an attitude adjustment procedure. Of course the team leader and myself would be discussing in front of the miscreant whether to have a blanket party, have him run in full gear around the barracks for an hour or two. Probably settle on scrubbing the latrine with a tooth brush after lights out. The only thing the rest of the squad knows is that this young man opened a can of "Ohhh, Shit." Let their imaginations run with it.

If this is his first offense it would be handled differently than if my wonderful Platoon Sgt decided he liked how I instilled leadership and a spirited and effective work ethic in my Marines. A lot of variables involved. Take you pick on how to handle.....

Remove them from formation and they can do pushups til formation is over, then a week at KP duty

Better yet, a brand new E-2 arrived in my unit. I returned from some meetings to find the coffee pot empty. The Operations Sgt was out. I directed The E-2 to make a pot of coffee. I took the time to instruct him on the task. Pvt. informed me his Drill Sergeant told him he did not have to make coffee for anyone. Mistake 1: He did not stand when I entered the room. 2. He did not address me as even Sergeant when he refused. Result and solution: Everyone in the Orderly Room drank the COFFEE I brewed before a fresh pot was made. Pvt. after that day never failed to acknowledge his 1st Sgt or refuse any task issued by a NCO. I never inquired about the conversation The Operations NCO had whith him. I do know my Ops Sgts ass was on fire after he departed my office.

Drop his whole squad. If he doesn't drop, then drop the whole platoon.
If that doesn't do the trick release the platoon then counsel him on his behavior and let him know that you will put an Article 91 in his file for insubordination.

I'd have him report to the orderly room and wait for the 1sgt, CO, and myself and tactfully remind him of UCMJ and then negatively counsel him for insubordination and let him know that if this attitude continues then I'll push for Art 15 and bad conduct discharge

Whoop his ass or make him do bends and thrust till I was tired..