In A&P school, the instructor for another class went out in the hangar with one of those 3' diameter balloons, and filled it.
The resounding
BANG was felt through half the facility and drew everyone else into the hangar to see how many had died. Just the instructor, and laughing from seeing the looks on our faces.
When something goes boom in an environment like that, it's never funny until you realize nobody was hurt and nothing was damaged (except eardrums and gray hair).