We learn part of Project Mayhem's mission when Tyler threatens Police Commissioner Jacobs. They intend for the common man—clerks, waiters, car washers—to rise up and take control of society.
TYLER: The people you are after are the people you depend on. We cook your meals. We haul your trash. We connect your calls. We drive your ambulances. We guard you while you sleep. Do not f*** with us.
It's the 99% rising up against the 1%.
If the police commissioner doesn't do what they say, Project Mayhem threatens to cut off his balls. While we're tempted to dismiss this as simply a crass threat, balls (and masculinity in general) are the driving force behind Fight Club. Bob lost his. In fight club, guys are constantly trying to demonstrate how manly they are through violent acts.
And the police commissioner? His balls "are ice cold." Because to them, a man who isn't in fight club, especially one actively trying to stop fight club, might as well not even have any balls…or a single ounce of testosterone in his body.