If you don't doodle, this means that your brain is as dead as a dodo. Doodling engages the left and right brains to upskill your visual language technique when listening at work.
These doodling lines only mean that drawing is a natural function.
When your brain is idle on lack of activity and stimulation, it walks randomly looking out for something interesting to draw about. What you are drawing simply is your own imagination.
Doodling is a way of communicating ideas through subconscious signals. All images have an urge to communicate and share their visions of the world and that what doodling means.