Instead of a picture of a sunset, your kid or yourself, you can have a randomly-generated GIF as lock screen wallpaper with GIF-Lock for your Android phone.
Shake your phone, and you'll get a new GIF. Once you find one you like, pin it, and you'll have an awesome moving wallpaper. You can't choose which GIF you get, so you might be shaking for a while. That could be time consuming, but anything in the name of the perfect GIF, right? [GIF-Lock]