It's the multiple sneezing that drives me nuts. Then too, the teeny little wimpy sneezes that sound like a toy poodle are a bit annoying as well.

My father had his own weird sneeze. He went "Chaaaaaaa....." in a very deliberate fashion. Not a sudden expulsion of air so much as a controlled evenly pressured "Chaaaaaaaaaaa......"   (in other words, you would not put an exclamation point after his sneeze).

My Mother does the multiple sneeze thing and it totally drives me up the wall! Never less than three, seldom more than five.