a you know - A short way to say something without explaining it, usually

A short way to say something without explaining it, usually to someone who doesn’t get it

'You know, the one who got suspended last week?' 'No, who?' 'You know, the one who tried to light the ceiling on fire.'

He said, 'You know, the one who eats the whole pizza by himself.' 'No, who?' 'You know, the one who eats the whole pizza by himself.'

She whispered, 'You know, the one who told the teacher about the prank.' 'No, who?' 'You know, the one who told the teacher about the prank.'