According to Encyclopedia Galactica (ooc: Wikipedia), Sto-Vo-Kor is the state of existence that Klingons believe that honorable members of their society will go to in the afterlife. Klingons believe that they will go to be with Kahless when going to Sto-Vo-Kor. Sto-Vo-Kor would be similar to the human idea of the Viking Valhalla and is seen as the Klingon's version of heaven.
With the similar mythology as our terran ancestors, the Black Fleet should understand that we are not to be underestimated and that Honor and Integrity are things that we value the most. Because of such honorless behavior as the so called Black Fleet of Sto-Vo-Kor has displayed, a more fitting name for them would be 'the Black Fleet of Gre'Thor'. I found the term in the same source.
Admiral, I would suggest in recompense for their arrogance, they should pay us at least the sum they asked. Then again, I'm just a Lieutennant, I don't want to overstep my boundaries.
However, my guns are at Your service.
Walter Nowotny.
If the stars should appear one night in a thousand years, how would men believe and adore and preserve for many generations the remembrance of the city of God? - from 'Nightfall' by I. Asimov The Outcasts consider Siniestre Nube a sacred place for several reasons. Early explorers discovered a jumphole within the depths of the cloud that leads to a strange world of ringed stars and strange craft. All ships in the burrial ground are placed facing that hole to honor the Alien Spirits. - An Outcast rumor