Don't remember my first time but I do remember my brother in-law's.  We were in the tent on a site near the Pickerel Narrows when he heard several splashes.  He woke me up saying that someone was throwing boulders into the water near our site and was completely freaked out.  I played along for a while until he was good and scared and then told him what the sound really was.

On that same trip we had a bull moose walk right through our campsite while we were doing dinner one evening.  That was the last straw for him.  Hasn't been in the wilderness since.   ;D