This is the classic one. I dreamt it years ago, but I remember it vividly. Now, I've read somewhere that we only ever dream in black & white, but this was so distinctly black & white - like an old movie, so different from my other dreams / nightmares - I have come to the conclusion this was an exception. It even had a soundtrack. Cue Mafia music...
We're in a stable. Large one. (Very Godfather-like, actually, only I had never seen Godfather at that time, and had actually never even been to a stable - but anyway...) I'm not there - luckily! There are two guys there. One is just hanging around, it seems, chatting. He carries a rifle, but that seems to be part of the job. There's nothing dramatic about the scene. The other one is preparing to have a bath in an old zinc tub.
All the time they're chatting idly - possibly they're brothers. Or working partners. Or something of the sort. The bather gets into the tub, sits down on his knees. Or stands on his knees, more precisely, there's no room to sit. (The tub's on a table, just like in this photo...)
Change of angle - the camera man (who must have been there, anyway, this is my nightmare!) goes past the first man to get a good shot at the bather. His friend puts his rifle down. Picks up an axe and goes over to the tub.
Loud music. Very dramatic all of a sudden.
The man with the axe says something, we can't hear him for the music, but the bather looks a little surprised. Then his puts out his cigarette, smiles friendly (really!) and plunges the axe into the bather's left thigh. Thick, red, curdling blood trickles out. (You'd expect it to pour out, but it didn't. Was too thick.) But that's not what woke me up. Not the blood, or the shock of 'why?'.
The music died the instant the axe was lifted and it was his scream, the bather's insane cry of pain that woke me up. I can hear him still.