「腦囟未生埋 / 腦囟都未生埋」

(pos:語句)
<explanation>
yue:#腦囟 本身都應該一兩歲就埋口，用嚟形容人好似BB仔咁#幼稚、唔成熟
eng:childish, immature; literally, the soft spot (on the head) has not closed
<eg>
yue:成二十歲人腦囟都未生埋，人哋講佢就信。 (seng4 ji6 sap6 seoi3 jan4 nou5 seon2 dou1 mei6 saang1 maai4, jan4 dei6 gong2 keoi5 zau6 seon3.)
eng:He's twenty but still childish; he believes everything others say.