Te sabes el resto de la historia.

English Translation

You know the rest of the story.

Does anyone know why this sentence uses ‘Te sabes’ instead of ‘Tu sabes??’

My dictionary gives the example:

se sabe todo el cuento de memoria
he knows the whole story off by heart

The pronominal form (i.e. saberse) can be used to emphasise how well the person knows something. As if they’ve already heard the story a thousand times already.