Squigglevision

It's a term for animation where the lines appear to squirm around, even when the object/scene is at rest. Apparently, it's even patented. It's part of the iconic look of shows like Dr. Katz:

And Home Movies:

Apparently the animation style is "fast and easy" to produce, although it does require multiple drawings:

In order to create the line oscillation effects that characterize Squigglevision, Tom Snyder Productions' animators loop five slightly different drawings in a sequence called a flic.…

Squigglevision is a post from CSS-Tricks