BUTCHER

For impaling enemies check your surroundings for hooks hanging from the ceiling and kick enemies on it.
Can be easily grinded on the very first level. Many hooks to hang on there. 😃

So... pressing the Interaction Button repeatedly apparently looks like your char is fapping... and the devs had their fun with that.
To get this achievement simply penetrate the interaction button repeatedly until your dude shoots a load. Yes. You can cum on dead people. 😄

If this doesn't unlock on your regular playthrough already, simply press DELETE. This button will make your char explode / committing suicide. Keep the button pressed so he will die again right after he respawns. Shouldn't take long to get this achievement.