WHAT IS THIS? It's a door built into the shape of a Villager's mouth.
WHY IS THIS? I don't know. I just thought it would be funny.
When is this? This door works in 1.12 and future versions.
How is this? It was incredibly difficult to fit all the redstone in the 6x6 area inside the villager's head.

Now that I've answered all your questions, this download includes 2 versions of the door. The first is a practical version, built at ground level, where anyone can walk in easily. The second is a lot less practical. because it has a body. The full body door has more parts, including a bouncer to launch you from the arms into the door. Be sure to crouch when using the bouncer; or it won't work, and you might get stuck.
If you build it in a 1.12 version, you can replace the jukeboxes with note blocks, but in 1.13 and beyond, they need to b e jukeboxes.

Have fun playing with this goofy door.