Hoo boy, i've had a lot of blunders in my time with this game. If i was going to pick one that was right to the point, i would have to say walking into Jamaica Plain when i was still a lower level, without a follower, only to get noticed by a couple dozen ghouls. It basically ended with me running away and being audibly afraid as they jumped at me and snarled. I ended up making it out but just barely.
This is War, Survival is Your Responsibility.