"We describe a hitherto under-recognized curious response in some individuals: of sneezing in response either to sexual ideation or in response to orgasm. Our review suggests that it may be much more common than expected. We surmise that an indiscrete stimulation of the parasympathetic nervous system may be an underlying mechanism to explain this and other reported unusual triggers of sneezing."
Bonus quote from the full text:
"From the sporadic reports in the medical literature, we surmised that the phenomenon of sneezing in response to sexual ideation or in response to orgasm is more common than recognized. As this is a problem that does not lead to morbidity and may be seen as embarrassing to discuss it may be under-reported. We performed a search of Internet ‘chat rooms’ where this problem may be discussed in an anonymous forum, using the Google search engine and with terms ‘sex, sneeze OR sneezing’. ...