[eddyfromtheblok]

This actually is not that uncommon, as there has always has been a subset of tech savvy users who want to run APKs not approved in the android market. I forwarded this to a few of them based on your comment, so thank you..

[Tiberium]

There's one thing that matters a lot: on modern Android versions you have to give the permission to install APK files separately for each app, which makes this exploit even less likely to work.