Black's Gym is where Holt Richter works as a personal trainer.
In "Sex and the Biddy", Donna signs Cleveland up for personal training after noting his weight gain and eating habits. Cleveland meets Holt at the gym and notes the good-looking ladies around although Holt points out that not only are they lesbians, they also have boyfriends. Cleveland is unable to handle the training and quits the gym, where a buff-looking man offers him a form-fitting girdle to make it appear he is still working out.