A person or group of people is said to eat their shit if they abandon all reason when forming a positive opinion.
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.
"It's one of those fuckin' animated movies that everybody goes and sees and fuckin' eats their shit and loves."