“打脸”，网络用语，字面意思是“a slap in the face”，通常指自己说了某句话或扬言做某件事后却没有履行（fall down on one’s promise），也可以指某人自信满满的断定事态发展，结果却出现与其预想完全（the complete opposite
I booked a hotel for our trip. If you don’t like it and want to book it yourself， well， knock yourself out.我已经订了这次旅行的饭店，如果你不喜欢这家想自己订的话，那你就订吧。
The US demands that Hong Kong police exercise restraint， while allows its own police to shoot protesters and deploys military.
