A few:
-Getting to the metal corridor and expecting 106 to pass through the middle. He did... halfway only, before he started chasing me D:
-Seeing 096 running full speed at me, emerging from the darkness... (even on Godmode it was scary)
-Various jumpscares and sudden insta-kills from 173 (especially in the Gas Catwalk). One instance caused me to not touch SCP for a few days/weeks
-And there was this one time a few months ago where, believing what my friend told me about 'Euclid' difficulty (supposedly) keeping 106 from spawning, I played on 'Euclid' and got trapped in a Lockroom. Having read up on the wiki about the whole "blink a few times and wait, and 079 will eventually open the doors for you" thing, I did so and waited a few minutes. After a while, I heard sludgy bubbling from (literally) underneath my feet, and 106 and I engaged in a short chase around the room before he killed me D': It was then I realised, my friend lied...
-There were also times when the MTFs shot me unexpectedly from the darkness, as well as when I thought they were 106/an SCP.
I stay on Godmode with noclip enabled most of the time, as I have a weak-ish heart, and even then the game terrifies me so much... D:
Saw this, weed a little, then realized one of them was 096 and calmed down instantly because I knew I hadn't looked at him.
SHAT MYSELF.