Summary:

If you have a sticky piston with three honey blocks facing up running on a fast redstone clock, when the player walks forward, they can walk through it without taking damage.

How to recreate:

1. Place a piston facing up
2. Place three blocks of honey on top of each other on the sticky piston
3. Surround the build with obsidian leaving a two block opening on two opposite sides to allow the player to walk through, also leave a one block gap above the honey block to ensure that the piston can extend.
4. Place a trail of redstone leading to a redstone clock with four pieces of redstone at the corners and a repeater on each side set to one tick (no clicking on the repeater after placing), except for on one of the sides replace one of the repeaters with a piece of redstone.
5. Place an observer block for a one tick pulse to start the machine
6. Walk into the honey blocks, you will notice that you player will walk into the honey block briefly before being spat back out on the same side you're walking in the block.
7. After a little bit, your player will walk through the honey block without taking damage!

 h6. Will post video once I can record it.