When you stabsomeoneand then proceed to fuck them in the hole you stabbed them in.
The detective said in a hushed voice "When we came through the door he pulled his crimson colored dick out of her stomach. Looks like he stabbed the now dead woman and murderfucked her."
When you attempt and fail at the act of murderfucking. Also, a vengeful hatefuck, possibly placing the victim in a near death type of situation.
Ronald - Lorrie cheated on me, so I tried to fuck her to death. But in the end all I could manage to give her was the attempted-murderfuck.
Bruce - I bet you feel like a failure.
To fuck so ferociously that one may mistake it for rape and murder if seen doing it. Usually involves intense choking, throating, sodomy, and all other sorts of holy & unholyness(see what i did there).