I usually would keep the scream turned on for parties as it was always a good laugh when it would happen. Sometimes I would forget to disable it. A couple years ago, my nephew who was 3 at the time was checking out my GB when the scream went off. He is permanently scarred of ever going in my basement again!
I remember as well a while back my wife and I went to a quiet restaurant on an early Saturday afternoon to get some lunch. The only other patrons in the place were 2 little old ladies. The restaurant had a room of pinball machines, and the Ghostbusters did not have the scream turned off. Well you should have seen these old ladies faces when that scream fired off... they looked horrified like they had just witnessed a murder. They gave me a nasty look as I came out of the game room, like I was the reason some woman screamed at the top of her lungs. Good times with the Fright mode!