5 realistic clouds in AE with no external plugins.

You know the good old movies shown in an old flickering and not very well timed film projector where you can see the different frames scrolling.

Here is an expression for having a marker trigger a squish and squash. Put the expression on Scale.

This example expression instructs a layer to be at the same position as the next higher layer in the Timeline panel, but delayed by a specified amount of time (in this case, 0.5 seconds). You can set similar expressions for the other geometric properties.

This expression is designed to track the position of a layer that has been parented to one or
more layers.

This Expression causes one gear to rotate at the proper speed when a second gear next to it is
rotated, so that the two gears stay meshed with each other.
by Fred Lewis

From Adobe's LiveDocs:
You can create an expression without using properties from other layers. For example, you can make a layer revolve in a perfect circle.

This expression maintains the objects apparent size as it moves away from camera.
It's helpful for taking a flat layout and making a "multiplane" layout from it for animation.