We had a guy who suffered from shell shock due to WW2. Some meetings he would be fine but every so often he would have a turn.
It took the form of this involuntary noise that went something like MEK MEEEK MEK MEK MEEEK MEEEK. It was something between a shout and a dog barking.
It was so loud that everything would stop for a moment. Frightened Children would start crying.
A visiting speaker who was not primed for this outburst asked to have the heckler removed! As I was just in my early teens I sat pinching myself to try and control my laughter. Crazy days!