Autoerotic Decapitation

An act of masturbation in which, while one pleasures themself, they decapitate themself with a rusty shovel or dime store katana at the verge of climax. Then, whilst their head rolls away, they attempt to catch the load in their mouth within the final three seconds of life.

Detective 1: "What do you think Bill, was this a murder?"

Detective 2: "Well, judging by the placement of the head and the trajectory of the wad, I'd have to say that this is autoerotic decapitation."