The 'Yo' app is taking over the App Store, and Stephen Colbert has a problem with it.

The app is built around one simple premise: being able to send the word "yo" to your friends that have the app. It's meant to be a reminder that you're thinking of them, without wanting to have a full-on conversation with them. A much more innocent Facebook 'poke', if you will. But the app already has raised a million dollars in funding, and has garnered more than 50,000 downloads. So, with that, Colbert has to ask, "Y?"

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