A man was arrested on Wednesday for making death threats against black students who attended the University of Missouri. A student at Texas A&M was arrested three weeks earlier for making "terroristic threats." Both were using Yik Yak, a social media app that has become very popular on college campuses in recent years.
What is Yik Yak?
It's an iOS and Android app that lets people post anonymous messages that can be seen by anybody within a set radius. For the most part, it's pretty innocuous (and often profane) stuff.
That seems harmless. What's the big deal?
Launched in 2013, the app was initially criticized for being a tool for cyberbullying on high school and middle school campuses.
A few high-profile incidents caused some schools to ban it. Technically, it was always off limits to users under the age of 18, but last year Yik Yak completely blocked use of the app near high schools and middle schools.
There have been some harassment issues at universities, too. Most worrisome have been threats of violence. Last year, a student at Towson University was arrested for promising a "Virginia Tech Part 2" attack on Yik Yak. An Emory student was arrested last month for writing that she would be "shooting up the school" the next day, which was followed with a similar incident at Fresno State University a few weeks later.
Yik Yak co-founder Brooks Buffington addressed the University of Missouri incident on Wednesday, calling it "upsetting and completely unacceptable."
"Let's not waste any words here: This sort of misbehavior is NOT what Yik Yak is to be used for. Period," he wrote. "It is not condoned by Yik Yak, and it violates our Terms of Service."
Why do college students love it?
After all of the negative headlines, Yik Yak might not seem like a fun place to hang out. But the social network also provides a place for students to gripe about finals, publicize house parties, and even share inspiring news.
lot of Yik Yak messages are simply jokes, like one of the most "upvoted" posts on the network from a University of Southern California student, who wrote, "Shoutout to my grandma cause that's the only way she can hear me."
Last spring, after a student at the University of Michigan wrote what purported to be a suicide note on Yik Yak, the community rallied around the user and used it start a campus-wide conversation about suicide prevention.
On Twitter, Yik Yak users express a common theme — a love/hate relationship with the app, which is commonly described as "addicting."
By Keith Wagstaff for NBC News