Before I get to the "definition", just hear this: never, ever, ever, EVER watch this video wherever you may find it because it leaves a troubling image burnt into your mind that depresses you whenever you think about it.
Anyway...
3 guys 1 hammer is a video that (
unfortunately) is an actual video of 3 men in the Ukraine brutally murdering somebody with things like a hammer and a screwdriver. The group of 3 men in the video are called the Dnepropetrovsk Maniacs. They mutilate a victim in the video named Sergei Yatzenko. I will not say
what happened to him except that he was murdered by these violent and
mentally disturbed men.
The 3 men are currently serving a life sentence in prison for their acts. Personally I think they should have done to them what they did to over 20 people in their montage of murder.
Again, please refrain from watching the video. Find info about it if you want, but please do not watch it.