trucker's sneeze
The act of unclogging one's nostril by plugging the opposite nostril and blowing with reckless abandon, so as to expel a large amount of snot or other matter with little concern for where it lands.
I didn't have a tissue so I decided a trucker's sneeze was in order. I'm breathing a lot better now, but I definitely got a dirty look from the old lady that was feeding the ducks.