Slippery physics is an irregular state of the game's physics engine, which allows the player to easily clip through walls using an object, amongst other things. On most platforms and versions of the game, it will be activated at random upon map load. On the Linux version, this state is always active. For the Windows releases, it's possible to ensure that slippery physics is always active by enabling compatibility mode in the game's launch settings. Selecting any of the operative systems seems to do the trick, though runners most commonly select Windows 7.
It seems that older models of AMD Radeon graphics cards run into stutter issues with compatibility mode.
There is a video tutorial on slippery physics, among other important settings, in this video.
Slippery physics demo video[]
A demo of most slippery clips for reference. One-take recording. Will tidy up later: https://youtu.be/_Ph-uhFO2yM
A tutorial on prop clips where the prop is tossed towards the player: https://youtu.be/mB9pq0S8yaI