When The Prof Introduces Foreign Key In DBMS But You Barely Know What A Primary Key Does

That face when your professor starts talking about Foreign Keys and relationships while you're still wondering why the hell your Primary Key isn't just called "ID" like a normal person would name it. Just standing there nodding like you understand the difference between CASCADE and RESTRICT while internally your brain is executing SELECT * FROM my_knowledge WHERE database_concepts IS NOT NULL and getting zero results back.