Spray-on knowledge

Knowing virtually nothing about a subject, except maybe a few key points, and using this knowledge to make yourself sound like they know what you're talking about.

On the surface, you look really knowledgeable, but if anyone asks any questions or prompts for more, then it quickly becomes clear that you actually don't know anything.

Closely related to bullshitting

Commonly used by university students who haven't done any reading for the seminar in five minutes, so they quickly cram in a few facts so they don't look like an idiot when asked about it.

Jack: you done any research for the seminar later?

John: Nah, will wing-it. Will Wikipedia it later to get a bit of spray-on knowledge, that'll be enough.

Jack: bit risky, isn't it? What if you get asked about it?

John: Never underestimate the power of the spray-on.