He yelled out once, and only then did the donkey move forward.
Tips
usage
Most often seen in the disyllabic 吆喝 (yāohe, to shout / to hawk) rather than alone. 吆 itself sounds rural / colloquial — fits scenes with street vendors, farmers calling animals, or workers chanting work cries.
memory
Mouth radical 口 + 幺 (yāo, 'small / tiny' phonetic). The 口 tells you it's something coming out of the mouth; 幺 carries the sound.
