Since some people are confused on how to do the glitch, I've decided to make a guide credits to large doug#3879 for finding the glitch (in order to do the glitch, you must not be in fullscreen)

first, make sure you are crouching. then, open up the "How to play" menu (B) which will allow you to move your mouse. after that, hold RMB (right mouse button) on the whitebar on the roblox window (make sure you release all keys except RMB). doing that will freeze the roblox window and the longer you freeze the window, the higher you will be launched into the air. (the glitches were done with the default package and normal body type) here is an example:

you can also do this to clip through walls, examples shown below in different levels:

this one doesn't always work 100% of the time, it'll take a few tries if your camera starts having a seizure, the starfish is the one that is causing the problem. you can only do the clip when it isn't near, or when your camera isn’t shaking. This glitch is now patched, you can still glitch through the wall but the computer won't open the gate until the 2 doors have been opened