The news has been dominated lately by incidents where outbursts of criminal behavior were organized via social media "flash mobs" -- but an equally interesting (and potentially even more dangerous) phenomenon is the unintended chaos resulting from event invitations which "go viral," resulting in huge numbers of people showing up and completely overwhelming the venue and security personnel.
This is happening more often than you might think. Last Saturday, for example, what was intended to be a small-ish pool party fundraiser at the Rams Pointe Apartments in Fort Collins, Colorado, turned into a chlorinated Bacchanal after organizers posted invitations on Facebook and Twitter. The invitations spread through the local high school- and college-aged population like lightning, resulting in an estimated 4,000 people descending on the mostly unsuspecting residents of the apartment complex (even the organizers had no idea what was coming).
One student, Wayne Campbell, was quoted by the local press: "The power of Facebook was definitely shown at the last party because it was ridiculous how many people actually showed up. It was just pure chaos." Fort Collins Police Lt. Russell Reed confirmed that "The social networking, Facebook, and texting turned it into an extremely large party."
Now, it would be unfair to say it's impossible to bring together 4,000 people ages 16-24 without violent disorder resulting, but I will note that often seems to be the outcome, especially when alcohol is involved -- and it always seems to be. No surprise, the Fort Collins "mega-pool-party" took a turn for the worse when a Colorado State University football player pushed an apartment security guard into the pool. The security guard responded by punching the football player in the face, and the gathering quickly degenerated from a pool party to a pool riot, with four people arrested and 10 sent to the hospital (some for alcohol poisoning).
As noted, this kind of things seems to be happening more often as time goes on. On June 3, 2011, a German teenager forgot to mark her birthday party as "private" on Facebook, resulting in 1,500 unwanted guests showing up at the venue in Hamburg. Actually this incident wasn't entirely unexpected: up to 15,000 people RSVP-ed for the invitation, prompting the teenager and her parents to cancel the party -- but by that point it was too late, as the invitation (and the event) had gathered its own momentum online. Hamburg police ended up sending 100 officers (including four on horseback) to control the crowd, with eleven party-goers detained and one police officer injured.
In July I wrote about a public disturbance in Hollywood which occurred after a popular DJ, Kaskade, tweeted an invitation to his 92,000 followers to attend a free "block party" to celebrate a film opening. So many people showed up that the flatbed truck carrying the DJ and his equipment had to be diverted down a side street, which only succeeded in spreading the chaos, as fans pursued the source of life-giving techno, apparently unfazed by traffic. A "near riot" ensued, as would-be party-goers became rowdy, jumping on and vandalizing police cars and throwing objects at the police, who responded by shooting a volley of non-lethal bean bags at the worst offenders.