If you go to the developer tools menu in Settings, then tap Launch Tools and open Bad Behavior, there's an option to "Report a WTF Condition". What is a WTF Condition? Why would an app report one?
In android development there are different logging levels. For example, there is
Log.v for verbose,
Log.e for level error,
Log.w for level warn. All these are visible in logcat during development.
Then there is
Log.wtf which is like
Log.e except it has level Assert which may actually terminate the program depending on the system. Ideally, this should never happen in your app.
wtf stands for "what a terrible failure".
Android docs on this: http://developer.android.com/reference/android/util/Log.html