Derived from адский — hellish. It can convey both the meaning of something which is good, strong or the opposite meaning of something bad.
Народ, кто возит детей, сообщите, пожалуйста, насколько щас можно посадить ребенка 5 лет и отвезти на дачу, и не иметь при это аццкий геморой? Какая щас практика: большой ли штраф, если чо? могут ли запретить ехать дальше?
Folks, those who drive children around, please tell if it is possible to have a five-year-old in the car and drive him to the dacha without getting a hell of a pain in the ass? What is the practice today: would the fine be expensive? Can they stop you from driving on?
(Greaff @ ЖЖ, 05/2009)