An act by which a victim is struck in the testicles after the assailant asks a question pertaining to the victim's knowledge of the city Bangkok or by which someone is struck in the testicles unprovoked and the assailant exclaims BANG COCK during the attack. In all cases the assailant will exclaim BANG COCK during the attack. Is a play on words pertaining to the capital city of Thailand which is Bangkok. Likely originated from peoples amusement with the name of the city sounding like "bang cock" and this amusement was then expressed in a physical act of throwing an object or striking, in some way, someones testicles while exclaiming the name of the city.
Bob: Hey bill do you know what the capital of Thailand is?
Bill: dude fuck you, not again..
Bob: **Strikes bill in the bag for the 3rd time** BANG COCK!!