(someone) bonk (someone's) head

Translations
ударить (кому-то) по голове
I didn't mean to bonk your head when I turned around.
Я не хотел ударить тебя по голове, когда повернулся.
Definitions
To lightly or playfully hit or tap someone on the head, often as a joke or to get their attention. The term 'bonk' suggests a non-serious, harmless action.