Today's comic isn't one of my best. I can see why some might misunderstand what's going on.
You're meant to think Ollie and Quentin are looking into a crystal ball. In fact the fish has sneezed and turned his bowl upside down. Ollie and Quentin wait for the dirt to settle before saying 'Gezundheit'. What's confusing is that you may think the fish has only sneezed in that last panel. Maybe the guys should be saying something like "Boy, that was some sneeze!"
Sorry, my bad.