[Update: After catapulting ahead with over 300 thousand users, Yo was hacked by three college students. According to TechCrunch, they’ve figured out how to reveal any Yo users’ phone number, send messages from that number, and spam usernames with unlimited Yos. So there you have it, even more annoying than before.]

Yo, an app for iOS and Android, describes itself as “the simplest & most efficient communication tool in the world.” Once you find other friends using the app, their names will appear in big block letters on your screen. Tap a name, and the message “Yo” will appear on that person’s lock screen, from you.

That’s all it does. It has already raised $1 million.

If you wish to communicate in a more sophisticated form, you’re out of luck. “Simple” and “efficient” communication, it seems, comes in the form of the word “Yo.” As the app says so eloquently: “Wanna say ‘Thinkin’ ’bout you’ to your love? Just Yo. Wanna say ‘Are you up?’ Yo.”

To be clear, funneling all communication into one two-letter phrase and hoping someone will interpret your intended meaning is not usually efficient. It might be succinct, but then so is throwing a brick through the window.

Because of its ability to interrupt your lock screen, however, I’d say Yo is the digital equivalent of a tap on the shoulder. Which is to say: It is occasionally annoying and always uncreative. There are so many other fun, inspired ways to get a person’s attention via social media: @signing his username under a funny photo on Instagram, texting her with just an emoji cactus, liking a Facebook photo from three years ago. The best messaging apps are the ones that act as a platform for inventive individual expression.

If this were just some gimmicky app that was plopped into the App Store by a few bored developers, Yo would not matter. But here’s the thing: Someone with a lot of money thinks this thing is worth more than $1 million. People are downloading it, catapulting it into the Top 100 apps in the App Store. It just surpassed Slingshot, a sophisticated new communications tool from Facebook.

Now, Silicon Valley heavyweights are defending it. Outspoken venture capitalist Marc Andreesen, for example, tweeted one such Yo defense Thursday morning. “[T]here’s a fascinating aspect lots of people are missing,” he wrote. “Yo is an instance of ‘one-bit communication’ — a message with no content other than the fact that it exists. … Other instances of one-bit communication: Police siren, flashing stop light, ‘Open’ sign, light turned on, taxicab roof indicator lit.”

Yes, we have symbols attached to machines to tell us when they’re moving fast, or when we should yield. But that has nothing to do with humans interacting with one another. Mobile technology allows us to go beyond blinking lights and one-word directions, and actually communicate with photos, video, or words made of — gasp! — more than two characters.

Still, you must be curious. So here’s a little run-through of how it works:

You’ll be welcomed and prompted to allow push notifications. This is Yo’s livelihood, so you must agree.

View photos Yo welcome screen More

After some throat clearing, you’ll be asked to enter your phone number so that you can see who else has Yo.

View photos Yo screenshot More

Story continues