If you have an android or apple device, you might have installed an app or game that is supported by ads. These can be intrusive and over the top but there are easy ways to curb them.
On android App Store or the jail break App Store you can get apps that help remove the ads. But there is a simple method. Turn data off, or if you can’t do that, put your phone in airplane mode. No Internet and the ads can’t be fetched. You might get empty boxes when you use the apps but at least there is no ads.