一瓶子不响，半瓶子晃荡

yī píng zi bù xiǎng , bàn píng zi huàng dangyipingzibuxiang,banpingzihuangdang

1. lit. a full bottle makes no sound; a half-filled bottle sloshes (idiom)
2. fig. empty vessels make the most noise

Study it in Yanamino