- po-faced
[po-faced 词源字典] - "Humourless and disapproving", 1930s: perhaps from po, influenced by poker-faced.
More
The po in po-faced, ‘humourless and disapproving’, probably comes from the use of po to mean ‘chamber pot’, though it might also have been influenced by the exclamation ‘poh!’, used to reject something contemptuously. In any event, the phrase is likely to be modelled on the expression poker-faced (early 20th century). This comes from the need to keep a deadpan face when playing poker. The game, first recorded in the 1830s in the USA probably gets its name from the German word pochen ‘to brag’.[po-faced etymology, po-faced origin, 英语词源]
