Find a sound that is already audible in the room - the hum of the PA, the swoop of a fan, the noise from the air conditioner, or traffic sounds coming through the window, etc. - and accompany it.
As you play try to imagine that this sound you are accompanying is being made by another person. Imagine what this person looks like, aspects of their personality and temperament, and try to make the audience aware of your mental picture of this person through your performance.
When you are satisfied that you have successfully conveyed your image of this imaginary partner, stop playing.
[Please contact me in the event of any public performance of this piece]