''Know Shaming'' is the petty social act of making someone feel smaller or stupid for literally not having known the information someone is telling them. Know shaming can occur in social or academic discourse, but also in interactions around media or celebrity consumption.
A: Have you heard of band XYZ?
B: No I Hav---
A: OMG! How do you not know about them!??!?!? Do you live under a rock?!?!! I knew about them ages ago like before they got popular.... YOU HAVE TO LISTEN TO THEM.
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A: Did you know..
B: No..
A: What OMG! Do you even read? So basically...
B: This is know shaming. How could I know anything about something before I know it?