Nothing.
Why should an expulsion of air from your nose and mouth caused by a nasal irritation warrant acknowledgement by others when no such similar acknowledgement is given for coughing, and farting is generally so embarrassing its ignored by everyone unless it's particularly foul-smelling and lingers? (In which case farting generally induces immature giggles and lewd remarks.)
Why should an expulsion of air from your nose and mouth caused by a nasal irritation warrant acknowledgement by others when no such similar acknowledgement is given for coughing, and farting is generally so embarrassing its ignored by everyone unless it's particularly foul-smelling and lingers? (In which case farting generally induces immature giggles and lewd remarks.)
Teenaged X-Files obsession + Bermuda Triangle episode + Self-led school research project = Atheist.