打幌子

打幌子

Literally means:

make a cover

Actually means:

be under the cover of sth

打 means wave; 幌子 is the cloth sign hanging in front of shop in ancient times, which tells its name and what business it deals in.

Metaphorically, it means doing something under the pretence of something else. Derogatory.

打，举；幌子，是旧时挂在小店门外的布招牌，上面写有店名和做哪种生意。

比喻假借某种名义做完全不同的事情。具有贬义色彩。