YikYak is an app that allows users to send, receive and see anonymous posts within a 10 mile radius.
Due to the anonymous nature of this app, this app tends to be used for threatening and bullying.
It is important to know that users can still potentially be tracked down, as the app uses location services to pinpoint where posts are coming from.
The app also allows users to vote on posts, either voting them up or down (Yakarma). This feature tends to encourage users to post inappropriate material, in an attempt to get higher votes.
The app is intended for a 17+ audience, but anyone can use this free app. Schools do have the ability to apply to YikYak to have a "geofence" around the perimeter of the school, making the app inaccessible.