Silly Social Norms

it's because in the dark ages, when people got the plague, saying "bless you" after someone sneezed was pretty much a must, as you were wishing them good health. A sneeze was believed at the time to be the first sign of the plague.

Sometimes I say "Bless my soul!" after I burp.

Because farts are disgusting and no one appreciates them. At least with a sneeze you know there won't be an after smell.

But it's worse to be sneezed upon, than to smell a fart.

people thought when people sneezed their souls temporarily left their body, so they said bless you so the devils couldn't squeeze in