rap (someone's) knuckles

a rap across/on/over the knuckles - a punishment which is not very severe but which warns you not to behave that way again.

She rapped my knuckles and sent me on my way.

• hard-on
• hard on heels
• hard on someone's heels
• hard on the heels of
• hard on the heels of something
• hard put to
• hard put to do something
• hard row to hoe
• hard sell
• hard stuff
• hard to swallow
• hard to take
• hark back to
• hark back to something
• harm a hair on head
• harm a hair on someone's head
• harp on
• harp on something
• has-been
• has got game
• hash out
• hash out something
• has more bark than bite
• Has the cat got tongue?
• Has the cat got your tongue?