Their Premium Friends, who pay a small fortune for the privilege of premium and advanced ticketing, will (temporarily) only be able to order tickets using the ticketing system's Best Available option. Later on, Choose Your Own Seat will become available.
Read all about it at the ROH blog and at Intermezzo.
And don't, just don't, insult your audience members this way.
UPDATE: Intermezzo reports on the major testing (and testing plan) failure that led to this situation.