Phrases using this construction are generally immediately followed by a conjunction and another clause describing the unreasonable or irrational action that is being performed by the subject.
From a logical viewpoint, people who eat their shit seem completely ridiculous. However, upon scientific inspection, it is revealed that eating one's shit is a social phenomenon closely related to, and indeed perhaps the same as, the bandwagon effect, which is well-documented in the field of psychology.
"Everyone eats their shit and wants an iPhone."
"Those kids eat their shit and spend all their time playing Smash Brothers."