Sexuality
Some people may sneeze during the initial phases of sexual arousal. Doctors suspect that the phenomenon might arise from a case of crossed wires in the autonomic nervous system, which regulates a number of functions in the body, including "waking up" the genitals during sexual arousal. The nose, like the genitals, contains erectile tissue. This phenomenon may prepare the vomeronasal organ for increased detection of pheromones.A sneeze has been compared to an orgasm, since both orgasms and sneeze reflexes involve tingling, bodily stretching, tension and release. On this subject, sexologist Vanessa Thompson from the University of Sydney states, "Sneezing and orgasms both produce feel-good chemicals called endorphins but the amount produced by a sneeze is far less than an orgasm. "According to Dr. Holly Boyer from the University of Minnesota, there is a pleasurable effect during a sneeze, where she states, "the muscle tension that builds up in your chest causes pressure, and when you sneeze and the muscles relax, it releases pressure. Anytime you release pressure, it feels good...Theres also some evidence that endorphins are released, which causes your body to feel good". Endorphins induce the brains reward system, and because sneezes occur in a quick burst, so does the pleasure. In non-humans
Sneezing is not confined to humans or even mammals. Many animals including cats, dogs, chickens and iguanas sneeze. African wild dogs use sneezing as a form of communication, especially when considering a consensus in a pack on whether or not to hunt. Some breeds of dog are predisposed to reverse sneezing.
Another less common verbal response in the United States and Canada to anothers sneeze is "Gesundheit", which is a German word that means, appropriately, "good health". Several hypotheses exist for why the custom arose of saying "bless you" or "God bless you" in the context of sneezing:

Some say it came into use during the plague pandemics of the 14th century. Blessing the individual after showing such a symptom was thought to prevent possible impending death due to the lethal disease. In Renaissance times, a superstition was formed claiming ones heart stopped for a very brief moment during the sneeze; saying bless you was a sign of prayer that the heart would not fail. It has also been stated that one says "(God) bless you" so that one does not catch the flu, cold, or any other forms of sickness.Other cultures have similar traditions:

In China, after a person sneezes they often say "百岁!" which translates to "may you live one hundred years!" the pronunciation is similar to "bless you" in English. pronunciation: [Bai Sui]
In Iran, it is common to respond to sneezing with the Persian phrase عافیت باشه âfiyat bâše, which translates to "health", similar to common European expressions. Indian culture is to respond with Krishna, similar to a blessing in western cultures. In Italy after a person sneezes the people present respond with the word "salute" (meaning: health). The louder the sneeze the more emphatic the response. In Slovakia, after a person sneezes, it is proper to say "Na zdravie!" which means "For health!