Hi, Welcome to JustAnswer! My name is Eric and I will endeavor to answer your question.
Are you male or female? If you could give me some indication of why you need to do this and why the men are gathered there, it might help me to advise you.
I agree that a hard one. How long do you have to prepare?
A lot of guys like magic but that seems kind of lame unless you can do some real cool slight of hand.
A demonstration of some kind perhaps, do you know marshal arts or can you come up with an antique, foreign or otherwise exotic firearm that many present will never have seen before where you can do a disassembly and reassembly demonstration?
Let me think some more.
OK, I will bet that a great many of them will not know how the corps came to be in existence in the first place. How about a history lesson on the corps before the corps and what events led up to it being formed?
By the way, Thank you for your service to our great country!
You are very welcome! Please let me know what you finally decide to do and how it comes out if are willing to do that! You can just post back here if you don't close the question. I will post back if I think of anything.
Also, please feel no obligation to click on the green accept button! Let this one be on me! Thank you for your service!