Had several scary experiences pre-Internet, and pre-Terb, but these two have stuck with me....
Last time I was ever at a SC was in the early 90's. I was there to see Christy Canyon on stage and the place was packed, as usual. I happened to notice some commotion near the front door, and the bouncer was manhandling some guys out of the club. Suddenly I see the bouncer dash back into the club and slam the door with a terrified look on his face, eyes bugged out, then I hear pop! pop! pop! pop! pop! I did not stick around to see what was going to happen next. I was afraid there would be more gun play, or that LE would arrive on scene, so I took the side entrance out. Turned out it was not the smartest thing to do, since to get to my car I had to walk by the guys who had just been kicked out who were gathered in the parking lot. I just kept my head down and acted cool, and never looked back.
Another time I was with an SP at her place, and shortly into our session she suddenly starts to have some form of bad seizure, and also has difficulty breathing. I immediately go for the phone and start to dial emergency, and she begs me not to, saying it's nothing to worry about and she has had this before. I brought her some water, lay her down in bed to rest and eventually she recovers, but I was pretty freaked out by now. When she finally seemed okay ( I was there for well over an hour by then ) she wanted to resume the session, but I was no longer in the mood so I wished her well and left.