To put on a fawning or obsequious smile/expression; to be all smiles in a servile way.
小明在请求别人帮助时，总是讪皮讪脸的
Xiao Ming always puts on a fawning smile when asking others for help.
Next Idiom
To put on a fawning or obsequious smile/expression; to be all smiles in a servile way.