I have managed to avoid any bad tripping partners but I once went with my 3 nephews (all brothers) in their 20's.  I didn't know this but one of them was prone to something called night terrors. In the middle of the night there would be loud screams coming from his tent until his brother could wake him.  It was a little unsettling to hear this the first time as I immediately thought the worst.  I imagined a bear or moose in camp but soon calmed down when an explanation was given.