someone who is not courteous, who has a foul mouth (see Molina)
Alonso de Molina:
atlacatlatoa. descortes o mal hablado. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 8r. col. 1. Thanks to Joe Campbell for providing the transcription.