rap somebody on the knuckles
US /ræp ˈsʌm.bɑː.di ɑːn ðə ˈnʌk.əlz/
UK /ræp ˈsʌm.bɑː.di ɑːn ðə ˈnʌk.əlz/
1.
to criticize someone for something they have done wrong
:
•
The teacher had to rap the student on the knuckles for cheating on the exam.
•
The manager rapped him on the knuckles for being late to the meeting again.