How to do the level 1 clip

Sprinting and crouching triggers a sort of "slide" (this is intentional by Lydia), one side effect is that this slide makes you go up ever so slightly.

The most difficult version (and the fastest version) of this glitches is where you get if you hold sprint, jump, and spam crouch, you'll get onto the bed. You can then clip through the back wall and land on a platform below.

There are slightly easier versions, but they're significantly slower than the earlier. You can clip onto the desk  using the same strategy of sliding onto it. If you proceed on getting to the bed, the same outcome as earlier stated will happen. If you go onto the TV after this, you'll get a hidden message from Lydia :3

A video of this glitch can be seen in my world record run.
