1. To hit or strike someone or oneself on the head. A: "How you'd get that knot on your head, John?" B: "Oh, I bonked it on the door a few days ago."I can't believe that ball bonked Mom right on the head! I guess this is why we're not supposed to play ball in the house.
2. To hit or strike someone or something. I must have bonked my arm at some point—look at that bruise!
3. vulgar slang To have sex. I heard that Katie and Brad bonked last night after leaving the bar together.
bonk
(bɔŋk)
1. tv. to strike one’s head. He bonked his head on the shelf.
2. tv. to strike someone on the head. I bonked John on the head.
3. tv. & in. to copulate [with] someone. (Usually objectionable.) She bonked him all night. At least that’s what he said.