to cover up the blame or wrongdoing of another person (see Molina; who gives this metaphor in the first person singular)
Alonso de Molina:
petlatitlan icpaltitlan nitlatlapachoa. encubrir culpa de otro. metaphora. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 81r. col. 1. Thanks to Joe Campbell for providing the transcription.