Used as an Expression.
Generally stands for " what do you want then? ". However with the correct slang and attitude it could also be used as " What The Fuck Do You Want Now"
Guy1 just walk away from the urinal before putting his "tool" away, and accidentally splash some for the droplets to the Nerd standing next to him. Nerd stared at Guy1.
Guy1: " Li Bae An Zua ! knn "