Have you used Yo yet? I'm getting pretty into it. It's a silly little app that literally just sends the word "Yo" to a friend's phone. If you have audio alerts turned on, a hyperactive little man also yells Yo at you, which is adorable and terrible all at once.

Yo is surprisingly popular and growing fast; last week the company received another $1.5 million in venture capital after getting an initial $1m last month. The ultimate goal is to build out an entire Yo network to try and rethink how notifications work. It's a particularly good example of the tech industry building a seemingly-ridiculous solution to a small problem that contains the germ of a much bigger idea within it. Yo might succeed or it might fail, but for the moment it's pretty fun to play with.

the lasting legacy of Yo should be to make the NSA seem utterly and ridiculously wrong

But whatever happens, the lasting legacy of Yo should be to make the NSA's position on collecting phone and email metadata seem utterly and ridiculously wrong.

Under Section 215 of the Patriot Act, the NSA is allowed to collect business records that might be relevant to a terrorist act. Under an expansive reading of this rule (are there any non-expansive Patriot Act readings?) the agency claims that it's allowed to collect records of basically every call and email in America. Not what's being said, but who's talking to whom and when. This is known as metadata, or data about data, and collecting it is ultra-controversial: on one side the NSA claims that information about network traffic is just another Verizon or AT&T business record, and on the other privacy advocates have struggled to explain just how personal and revealing metadata can be.

But spend a couple minutes with Yo and you'll get it.

There isn't any other data — there's just Yo

Yo represents the radical idea that literally any communication from people in your network is valuable to you — it reduces the actual content of the message to secondary status and lets you fill in the blanks. A Yo from my wife at 10am means something different than a Yo from a coworker at 10:15, which means something different than a Yo from a friend at 11. You can set Yo up to turn your air conditioner on and off. A Yo from Amazon might mean that a package has arrived; a Yo from Netflix might mean that the latest season of Scandal is now available to stream.

Written letters to emails to IMs to tweets to Snapchats to Yo: human communication has gotten shorter and more complex all at once. Yo explicitly highlights the value of metadata: who sent you a message and when. There isn't any other data. There's just Yo.

In this context, the NSA's position that it should be allowed to collect the bulk metadata of millions of phone calls and emails is insanity. Just draw the thread out to Yo: if the NSA is allowed to collect metadata from Yo, it will straight-up be collecting the communications of millions of Americans, because there simply isn't any other data to collect. When the NSA allows the FBI and CIA to conduct thousands of searches for the communications of Americans, the charade of getting a warrant to dive past the metadata will be rendered inane: you can talk to the judge, but all you're gonna get is Yo.

you can talk to the judge, but all you're gonna get is Yo

And when people are killed based on metadata, as ex-NSA chief Gen. Michael Hayden has admitted, Yo will find itself behind the trigger of a gun.

There's a lot of conversation in Washington about the NSA and bulk metadata collection; a handful of bills have appeared, and Obama has proposed ending the program if Congress authorizes the NSA to quickly collect similar data from phone companies. (Which may or may not actually accomplish anything, really.) A couple court cases have divided appeals courts and the issue might end up at the Supreme Court.

In short, everything's up in the air. The issue feels wonky and the solutions are caught between the legitimate needs of law enforcement and the seemingly endless complexity of digital communications.

But it's actually pretty easy to understand. Just download Yo and send a couple Yos to your friends. Ask yourself if the government should be allowed to collect that information without a warrant.

Yo.