There is a common belief that sneezing x amount of times (somewhere between 7 and 10) is the equivalent to having an orgasm/will cause an orgasm. However, there is no scientific evidence to back up the claim, it is more of a "he said/she said/have you heard" sort of deal. According to Snopes.com, the belief is most likely stemmed from a misquotation of a sex therapist's words, mistaking "An orgasm is just a reflex, like a sneeze" for "An orgasm is just like a sneeze."
Basically, it's an urban legend of sorts, kind of like the whole "If you make that face too much, you might be stuck looking like that forever," so I guess the scientific thinking principle that fits best with this is "Extraordinary claims require extraordinary evidence."
Sneezing feels awesome. Sneezing multiple times feels AMAZING. But there is absolutely no scientific proof that sneezing seven times in a row will cause an orgasm, just as there is no proof that sneezing seven times is the same as having an orgasm. As far as anyone knows, it is simply a reflex; a reflex that feels amazing, but a lot of things feel amazing. Just because a sneeze feels awesome doesn't mean that you're having a mini orgasm out of your nose.