system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When i feel a half-sneeze creeping through my sinuses and my eyes start to tear up, what is actually happening?

You all know the feeling when a sneeze just won't fucking happen. The abstract burning, the watery eyes - what is actually going on in my sinuses when this happens?
gpt
A sneeze is a semi-autonomous reflex that requires many muscles activating together to perform. Normally, your body isn't capable of launching so much air at once to clear your nasal passages. Many muscles have to contract at once to force that large amount of air and to also protect the body from the high pressure generated by the sneeze.

Imagine a sneeze as a space rocket launch. Mission control has to make sure that every part of the launch is working properly before starting the launch. Even during the launch sequence, there are many steps that have to be performed in order to make sure that the rocket is completely unobstructed, the fuel ignites properly, the rocket is shooting in the correct direction, etc. 

However, when something goes wrong in the sequence, the launch is aborted. However, some parts of the launch sequence have activated and your body will feel only a half-sneeze as certain muscles have contracted but the rest have not.