From Longman Dictionary of Contemporary Englisha rap on/over the knucklesa rap on/over the knucklesCRITICIZE a) informal a punishment or criticism that is not very severe The New York Post received an official rap over the knuckles for the way it reported the story. b) if someone gives a child a rap on the knuckles, they hit them on the back of their hand as a punishment → rap
Examples from the Corpus
a rap on/over the knuckles• Was it going to be a rap on the knuckles for quality? 