Translation guide
The English word 'bonk' has two main uses: a light, hollow-sounding hit (often to the head) and British slang for sexual intercourse. This guide focuses on the hitting sense, which is more likely to be needed by learners.
Expressing a light, often comical hit that produces a hollow sound, typically on someone's head.
An onomatopoeic word that mimics the sound of a light, hollow hit, often used in manga or casual speech. It can be used as an adverb or a noun.
彼は弟の頭をポカッと叩いた。
He bonked his little brother on the head.
Expressing the slang meaning of 'bonk' as sexual intercourse, primarily in British English.
Japanese has many slang terms for sex, but none directly correspond to the lighthearted, almost comical tone of 'bonk'. The most neutral slang is エッチする (ecchi suru), though it's slightly childish. For a more adult but still casual term, use やる (yaru). Be aware of context and relationship.
Direct translation is impossible. Choose a slang term based on the level of vulgarity and the relationship. エッチする is softer; やる is more direct.
昨日彼女とエッチした。
I bonked my girlfriend yesterday.
There is no single Japanese verb that exactly means 'bonk'. Using a general verb like 叩く (tataku, to hit) without an onomatopoeia will lose the hollow, comical nuance. Always pair it with an onomatopoeic adverb like ポカッ or コツン to convey the sound.
頭を叩く
to hit the head (not necessarily 'bonk')
ポカッ suggests a slightly softer, more hollow sound, like hitting a balloon or a cartoonish head. コツン is sharper and harder, like knocking on wood. For a typical 'bonk' on the head in a comedic context, ポカッ is often the best choice.
Another onomatopoeia for a light, sharp tap, like knocking on a door or tapping someone's head. Slightly more delicate than ポカッ.
先生は生徒の頭をコツンと叩いた。
The teacher bonked the student on the head.
A general phrase meaning 'to hit lightly'. It lacks the onomatopoeic nuance but is widely understood. Use with a location like 頭を (on the head).
彼女は冗談で彼の頭を軽く叩いた。
She jokingly bonked him on the head.
A variant of ポカッ, also onomatopoeic for a hollow sound. Less common but used in similar contexts.
漫画でキャラクターがポコッと叩かれるシーンがある。
In the manga, there's a scene where a character gets bonked.
Those two are bonking again.
The direct loanword for 'sex'. It's more clinical and less slangy than 'bonk', but it's widely understood.
彼らは毎晩セックスしているらしい。
Apparently they bonk every night.