rapping someone's knuckles

Verb

rap someone's knuckles (third-person singular simple present raps someone's knuckles, present participle rapping someone's knuckles, simple past and past participle rapped someone's knuckles)

1. (literally) to tap one's knuckles on an object such as a desk or wall to attract attention or as a signal of commmunication.
   • Just rap your knuckles on the wall when you're ready to go.
2. (dated, idiomatic) to give someone a punishment.
   • If the sales department doesn't get organized soon, the CEO is going to rap their knuckles.
3. (archaic, literally) to strike someone on the back of the hand usually as a method of punishment.
   • In the old days the teacher would rap someone's knuckles with a ruler if they misbehaved in class.