You get your bell rung hard enough, you are gonna experience the Fencing Response. Some people think this reaction may help an injured person keep their throat open to assist breathing, but this is not a proven theory.
Words Words Words
When a person experiences an impact that’s strong enough to cause traumatic brain injury (TBI), such as a concussion, their arms often go into an unnatural position. This position — forearms extended or flexed, usually in the air — follows the impact and is known as the fencing response position. It lasts up to several seconds after the collision.
Additionally, it's what happens when you fuck around and find out.