I asked this over on travel.SE, but they weren't pleased and I was directed here.
For those out of the loop, this (hopefully) satirical facebook event has garnered quite a lot of attention, with one million people confirming they'll attend, and a further ~900,000 saying they're interested.
I don't for a second imagine they'll all turn up, but if they did, what would transpire? Would the US military actually kill a million people naruto running towards Area 51? What if it was only 10,000 people?
This question is reasonably similar to If a million heavily armed children stormed Area 51 what would they do?, except in this case, the stormers aren't children, nor are they heavily armed - they're just a bunch of likeminded adults taking a joke a little too far.
This question is also very similar to Storming Area 51, as pointed out in the comments - though I would disagree. There are however many thousand tactics and strategies to defeat this "invading" "force" of jokesters, but I'm more interested in what is actually likely to happen. Sure, it's entirely possible for the US military to bomb the crowd, but I don't think for one second that they would.