mlaaah! Posted in M Best definition mlaaah! Sound made after saying something funny or sarcastic. Must be pronounced while sticking out your tongue. A regional dialect unique to South Texas. “If you say that again, I’ll cut you, Mlaaah!” How satisfied are you with the definition? Looking for mlaaah! meaning? Delighted that you discovered the greatest determine on our web site! Recently this definition was actually observed 4 times.