Just make sure you go with the grain, not against it.
A brow brush is the gentle caress of a woman's brow against the underside of your balls.
DO NOT GO AGAINST THE GRAIN
Part 3 of D Procedure. It is optional, which means that it can be done with or without the rest of D Procedure. It merely supplements the experience.
Khalifa got his Brow Brush in the Charles Activity Centre.
Alexa cannot receive a Brow Brush as she is a female.
I went against the grain with my Brow Brush and lost both nuts in the process.