MUJERON MISPELLING of a form of the verb 'MUGIR', to moo. 3rd person plural of the undefined mode: MUGIERON, and not MUJERON, as it is an irregular verb. There is an complex and unpredictable way of using g or j in some verbs or adjectives, according to the evolution from old spanish and the Spain region where it was mostly used in the middle age and before that.
Used in Spain as well
"The cows mooed when we approached them. Las vacas MUGIERON cuando nos acercamos a Ella's."