The only example of pure Black Speech is the inscription on the One Ring:
Ash nazg durbatulûk, ash nazg gimbatul,
Ash nazg thrakatulûk agh burzum-ishi krimpatul.
Some other words in the Black Speech:
Ash – one
Nazg – ring (finger ring); as in Nazgûl (‘ringwraiths’)
Burzum – darkness; as in Lugbúrz (‘dark-tower’), the Orcs’ name for Barad-dur
In the films, linguist David Salo constructed two phrases in the Black Speech, based on what little words and information have been provided:
Gu kibum kelkum-ishi, burzum-ishi. Akha-gum-ishi ashi gurum.
("No life in coldness, in darkness. Here in void, only death.")