Okay, we get it already. Anyone can get a large group of people who assemble suddenly in a public place, perform an unusual action for a brief time, then quickly disperse.

It seems like everyone is getting in on the this new form of viral marketing from comedy troupes to PR firms and even The Today Show. The latest? Ballroom dancing in a supermarket.

The big flash mob event to go viral came from Improv Everywhere when they froze Grand Central Station on January 31, 2008.

When corporations see a good thing on YouTube and decide to copy it.

So let's take it into the corporation! Onto Best Buy!

Did you hear Michael Jackson died? Let's honor him with a flash mob!

What about public transit? Check.

And finally to round out the year, elves in Union Square. What a production this has become.

20th Anniversary of "Say Anything" Flash Mob

This one is actually funny, a fat guy in a red Speedo starts a flash mob on the beach.

Flash mobs are fun and everything, but have you tried doing one without pants?

How can we make flash mobs even more played out than they already are? Stop! Hammer Time!

And you know when it' hits Oprah it's all over.

Now let's mix one popular meme with another and see how that looks!

The most flamboyant of flash mobs.

Improv Everywhere's "I Love Lunch," which features the Today Show's Ann Curry.

Hey we have train stations in Belgium too, let's jump on this trend before it leaves the station!

Ballroom dancing in a supermarket.