I think most people know that it’s just a joke but just “signed up” so they can say they they did. Most wont try it....
That said, I’ll bet that a fraction of a percent of those million plus that did sign up will try to rush the base. Depending on how many actually try will determine the outcome...less than a hundred will likely just result in arrests. A larger group rushing the base will probably result in a few getting shot and the second those first bullets hit them, that mob will turn around and run screaming in the other direction...”THEY ARE REALLY SHOOTING AT US!”
And then there will be sorts of news stories from those that run away about the “excessive force” shown and how they were all just victims and that didn’t do anything to warrant that response...