Two apps in Google Play that collectively had been installed over 1.5 million times used a creative method to load ads without even showing them to the user. The stealthy technique completes with an automated ad-clicking process that contributes to increased revenue for the author. Users that have installed these two apps are advised to remove them, lest they want to experience the negative impact they have on the Android device. Both apps have been removed from Google Play, but hundreds of thousands of users may still have them.
Source: https://www.bleepingcomputer.com/news/security/android-apps-with-15m-installs-boost-ad-revenue-with-ghost-clicks/