boink

1. hit or strike (someone or something).

   he bonked his head on the plane's low bulkhead

2. have sex with (someone).

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

3. (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

1. an act or the sound of hitting someone or something.

   give it a bonk with a hammer

2. an act or instance of having sex.
3. a level of exhaustion that makes a cyclist or runner unable to go further.

   we had the bonk when we were saddle sore

1920s: imitative.