Black market rate means that you go to a subway station, locate a sketchy "banker" and exchange some currency. Rules and regulation apply only above the ground

Black market rate means that you go to a subway station, locate a sketchy "banker" and exchange some currency. Rules and regulation apply only above the ground level. The alternative is going to the bank, waiting 2 hours in a line, and getting half of what that dude would've offered you, because the central bank decided that its currency is strong and should be valued that much.