In August Underground Mordum, there was a retarded character called Maggot who fucked his sister on a regular basis which pissed off her serial killer boyfriend.
Maggot also did a bunch of other fucked shit with the pair of them when they went on their killing sprees.
During one of these murder sessions, after he screwed the corpse of some young girl, he ended up getting so upset/excited that he rolls around on the floor and slits his own throat while the other two were arguing with each other.
So maybe that's what Endeavour was referring to. (Minus slitting his throat)