I got a new 32 GB SD card and was in the process of transferring files when I noticed a folder on my internal storage labeled "TapJoy". Inside were three small .png files related to TapJoy but also a couple of 1MB video files that were advertisements. One was for Verizon and one was for Progressive Insurance. Googling around I've learned that TapJoy attaches ads to apps, frequently to game apps. When you download the apps the ads are stored in your internal memory storage until an opportune time for it to play, usually while you are playing the game. In some cases you are "rewarded" with virtual game money if you watch the video ad.
I find this type of marketing to be disgusting. I believe the game the ads came packaged with was Baseball Superstars 2012. I looked at the permissions for this game and saw nothing about the fact that it would deposit 2 MB worth of video files on my phone's internal storage.
I recommend that anyone reading this go into your file manager and see if you have a folder named TapJoy. Inspect the contents and delete them. From what I've read the ads may ride their Trojan Horse--the app you installed that uses TapJoy--the next time you activate that app. Please post if you find anything. I'd like to see how widespread this advertising scheme is.