If you will try to get this achievement passively but also quickly, you would need to go into servers which have, Lags, Bad hosting, Huge modpacks.

If you wanted to do this achievement in singleplayer, you would have to play on pretty big modpack and do pretty crazy things, for an example blowing up a wall of props, or even a mountain of them,
or fighting alot of NPC's without clearing the ragdoll's.

Disable every mod, go to settings, put Garry's Mod from fullscreen to a window if you have not.
After that go to the default version of Garry's Mod, open an autoclicker, close all the tabs except the autoclicker and steam.
Now you will have to setup steam start game button and the Garry's Mod exit button so they overlap, after that u activate the autoclicker at preferably 1 click per minute.

rate 5 stars + help me im locked in a basement