hit or strike (someone or something)

he bonked his head on the plane's low bulkhead

have sex with (someone)

I don't think that bonking the boss is a wise career strategy

(of a cyclist or runner) reach a point of exhaustion that makes it impossible to go further

I bonked and couldn't pedal another stroke

an act or the sound of hitting someone or something

give it a bonk with a hammer

an act or instance of having sex

a level of exhaustion that makes a cyclist or runner unable to go further

we had the bonk when we were saddle sore