An insult, stating the the other individual should feast upon feces,

To take a bad fall, similar to the terms "eat snow" in snow skiing and "eat dirt" in biking. Eat shit can conveniently be used to describe a fall on any kind of terrain, including gravel, concrete, snow, ice, water, or anything you can think of. It is a commonly used term in waterskiing.

Like getting fucked over when you crash and it is very paintful

To basically sit around doing nothing of any productive value. Or another person or group of people participating in an activity that to you is a waste of time and is of no interest.

The perpetual process of doing nothing productive. Considered a life style by some, it involves procrastinating, smoking weed all the time and generally wasting unused potential.

the act of putting a bit or chunk of feces in one's mouth, and then swallowing.

The act of eating shit, or telling someone to eat shit as an insult.