"hrth" is a term that means everything and
nothing at the same time.
One could use this term as a game of sorts, where a few people would
act as though they completely understood each other while using this term, to intentionally confuse people.
Person 1:
Man, that was hrth
Person 2: I agree whole-heartedly
Victim:
Umm, "hrth"?
Person 1 + Person 2: What, you don't know what hrth is?
(drags on)