to throw things at the most narrow (or thinnest) part
Orthographic Variants:
çantlein ipan niccuepa
Alonso de Molina:
zantlein ipan niccuepa. (pret. zantlein ipan oniccuep.) echar las cosas ala mas flaca parte. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 14v. col. 2. Thanks to Joe Campbell for providing the transcription.