The “Wiggle” expression is one of those tools that you learn after playing with After Effects for a while and opens up a whole new world of customization to the effects and looks you are trying to get with text, 3D Cameras, and live action video. The Pixel Lab does a grab job of briefly describing the basics and a couple of techniques to use the Wiggle Expresion. Remeber, even though they are talking about using it on a 3D camera, it can be applied to any layer individually and have the same effect.