Before I get into the tutorial, you might wanna have some good armor for this glitch.
1.) Get a bunch of Ender Pearls, a Minecart, or a boat.
2.) Put the Minecart/Boat down.
3.) Get inside of the Minecart/Boat.
4.) Look up in the air and start spamming the throw button for the Ender Pearls while in the Minecart/boat.
5.) Eventually, it'll teleport you, to where you threw the ender pearls.
6.) Now, if go into 3rd person. It should look like you are still sitting down. If it does look like your sitting down, then you've done it right.
7.) And that is how you do it.

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