Katrin wants to make some exercise with a rubber-band.
She begins with easy-streching, but then she sees her slave peeping...
She decides that he needs also some exercises, order him to the floor... why not make the exercise on him!
She steps on him and continues with the rubber-band, crushing him under her sneakers.
It mus be more painful, so she moves to his face, still playing with the rubber.
Now on his face and throat, the training is much more intensive... especially his pain ;-)