it lets you accepted anonymous messages and read chatter within a radius. >> we saw a problem on the campus where there was a select few twitter accounts which kind of held the campus voice. we said, everyone should be able to have that power. we gave it to everyone. >> fast forward a year later, the app is exploding on college campuses across the country. >> basically every campus in america. >> vanderbilt university, someone posted about his brother getting a full body blood transfusion. 700 people showed up in the first hour to see if they were a match. >> the downside? anonymity can lead to bullying or harassment. >> we have filters for names, for personal information. you know, just generally offensive things. >> yik yak still had growing