to make something splash, spatter, get spotted (see Karttunen)
IPAspelling:
tʃɑtʃɑpɑtsɑ
Alonso de Molina:
chachapatza. nitla. (pret. onitlachachapatz.) chapatear por lodazales. Alonso de Molina, Vocabulario en lengua castellana y mexicana y mexicana y castellana, 1571, part 2, Nahuatl to Spanish, f. 19r. col. 1. Thanks to Joe Campbell for providing the transcription.
Frances Karttunen:
CHACHAPATZ(A) vt to make something splash, spatter, get spotted / chapotear por lodazales (M), patalear en el barro, salpicar, manchar algo (S) [(1)Cf.74r,(3)Tp.184]. See CHAPĀN(I). CHACHAPACHILIĀ applic. CHACHAPATZ(A) CHACHAPATZALŌ nonact. CHACHAPATZ(A). Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 44.