system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do some people regularly sneeze a specific number of times whenever they have to sneeze?

For example, almost every time my dad sneezes they always come out in pairs, A coworker sneezes in trios, and I know of a guy who sneezes 8 times every time he has to sneeze. Why is that?
gpt
Sneezing is usually caused by nasal irritation.  Once the signal is sent from the nose to the brain and the rest of the nervous system, a sneeze develops as an automatic response across many parts of the body.  One good sneeze may be enough to get the irritant off the nasal mucosa, but the nervous system may still think it needs to sneeze, as the chemicals that sent the signal (histamines) may still be sending the signal.  If so, it will keep making a person sneeze involuntarily until the signal finally stops firing.

In many ways, especially when nerves are involved, your body can have a mind of its own sometimes.

Given that the body may have a common amount of time until the signal stops, some people may commonly sneeze a specific number of times on average.