Meaning of dāi zi:
dāi zi
呆子
Noun
fool; sucker
Tā jìngrán wàngle yàoshi, zhēn shì gè dāi zi.
他竟然忘了钥匙,真是个呆子。
He actually forgot the keys, what a fool.
Tā zhēn shì gè dāi zi, shénme dōu méiyǒu fāxiàn.
他真是个呆子,什么都没有发现。
He is truly a sucker, he didn't notice anything.