Generally, I don’t think Trojans and other things that can compromise your phone are funny. This one however is amusing and it's called Android.walkinwat. The app is on file sharing sites where pirates frequently download apps without paying for them.
It poses as the Walk and Text app that is really on the market. When the pirate installs the app it grabs some details from the phone and then gives the user a message telling them they were busted pirating an app.
The app then takes the numbers from the pirates contact book and sends out the text you see above. I guess they think embarrassing people is a good way to get them to stop pirating.
[via PC World]