What is the most disgusting thing you have ever witnessed?

In my freshman year of high school, there was this pair of creepy twins that kind of inserted themselves into my friend group. They had poor boundaries, and the easiest way to describe an interaction with them would be if Gail the Snail from Its Always Sunny had a twin and very religious. Anyways, one day during lunch, one of the twins was eating a salad and started to rear her head back to sneeze. I watched in horror as she full on open mouth sneezed into her salad, stared at it for a moment, then started eating it again.