Before the invention of doors, entering a new building was a lengthy, painful process

That is a great way of paralyzing yourself .... and killing yourself instantly if you do it with enough force

Here's the story of Serbian player Boban Janković, who in 1993 paralyzed himself when he smashed his head up against a padded concrete post.

https://www.youtube.com/watch?v=1cfPr-D_4iY

As funny as it looks, smashing your head up against a wall is absolutely dangerous. If your head is just at the right angle with enough force behind it, you can paralyze yourself ... with just bit more force, you kill yourself.

The invention of CTE

Fun fact: doors were invented before buildings

More of a rugby helmet. Mr Burns' helmet always confused me until I learned it used to be rugby. *Forward pass was introduced in 1906. While I'm not sure how it was played I imagine it was more rugby style than what it is today.

Username checks out.

All of these convenient doors made us lose the ability to clip through walls

Why lab technicians are required to wear stain-resistant lab coats and eye protection.

Dam men are stupid sometimes

And they're still not safe, not until they invent inertia dampeners.