I don't even know what that means
This is what you say when you're trying to sound cool but you're just a hot mess inside.
He said, 'I don't even know what that means,' after I explained what a video game was.
She said, 'I don't even know what that means,' when I told her I passed the test.
He said, 'I don't even know what that means,' after I asked him what a paragraph was.