Do not cause trouble in a place where you must be on a regular basis. Often used with workplace romances but can also apply to relationships with students at your school or starting shit in general.

When you eat dirt for the first time and leave your family to build a shack in the woods

This phrase means "do not have romantic relationships with any co-workers." Basically, you don't want to make yourself uncomfortable (by potentially having a romantic relationship get ugly, or "shitting") at the place where you work ("where you eat").

This expression refers to doing anything that would jeopardize something important or essential to you. A common example of shitting where one eats is engaging in a romantic affair with a co-worker, but lying to your roommate or stealing from friends also fits this expression.

Don't behave in a way, or make choices, that will ruin something you depend on.

do not scew up or screw someone from where you work and or play.

An ancient ecological principle which is to be taken literally. Applies especially to heavy industrial chemical pollution, which when allowed to be generated and dumped freely into a closed ecosystemThe Earth due to laissez-faire environmental regulation and corporate neglect, generally results in deleterious effects to all organisms and human health.

Most Infamous example of corporate maleficence was the Bhopal Chemical Disaster.

Effects including but not limited to: Infertility, unplanned gender disruption, cancer, death, mental disability.