Some years ago in a computer science department I heard the term “cocktail knowledge” to refer to the knowledge that someone has on a subject when they can name techniques, results, and people but they don't have a very deep understanding into what they talk about, even less a clue about how to implement it themselves. Today I tried to find that meaning for “cocktail knowledge” online and I couldn't find a reference to this term. Has anybody heard this term before? or did I just invent a new term?
One could speak of having cocktail party knowledge of a subject— a superficial recollection of some terminology or figures and high-level concepts that would enable one to participate in a conversation on the subject socially (as at a cocktail party), but not knowledge that could be discussed in an academic setting or applied in a professional one.
I would not call it a well-established idiom, but simply a colorful expression.