Definition of and one knows it in English:

and one knows it

phrase

  • Said to emphasize that someone is well aware of a fact although they might pretend otherwise:

    ‘that's nonsense and you know it’
    • ‘Oh my God, Rachael, that's not what I meant and you know it!’
    • ‘They're breaking the goddamn law and they know it!’
    • ‘That's a lie and you know it!’