You can report an app for abuse by clicking Report/Contact this App at the bottom of any canvas page within the app.

If you are not currently using the app but would like to report it, simply go to the app's profile page on Facebook, and click Report App towards the bottom of the left column.

In addition, we’d recommend that you contact the developer who created the app directly so they’re aware of your report. You can report this to the developer by going to the app's profile page and clicking Contact Developer towards the bottom of the left column, or by clicking Report/Contact this app at the bottom of any canvas page within the app.