I got the mother of all fart stories.
In secondary school year 8 during a physics exam, this fat kid in the front of the class farted really loud, kids started giggling then the giggling quickly died down and this awful smell spread through out the class as the teachers hushing everyone. A girl right behind the kid started gagging from it and really sounded like she was going to vomit, then a boy right beside her vomited all of his desk and exam. As he vomited a bunch of other kids started gagging, I was in the back with half my face buried in my jumper, I really thought everyone was dying.
They ended up cancelling the exam and we did it the week after. Rumours spread like crazy and everyone thought the kid who vomited first had aids, school days.