Buddy sneezes like crazy when he gets overly excited. One time when my daughter came after not seeing him for over a year, he went into a sneeze fit that scared the you know what out of me. He couldn't seem to catch his breath.
He also sneezes 3 or 4 times when he greets people he likes when we are out walking. It happens inside the house too, which is air conditioned 24/7. I think it's a nervous habit.