Now by this, I don't mean specific story moments or anything like that; I'm more referring to largely spontaneous events in a game that made you reel back in reverence of the awesome that has just occurred. Perhaps an example is necessary.
I was playing Skyrim yesterday (I've a feeling that a lot of the moments are going to be from open world games like this one) and I decided to murder an entire village of Orcs. Do not ask why. Everything was going swimmingly until I faced off against the chief. This fucker refused to die, no matter how much I punched him. I then decided to lure him outside and let the Giant take care of him. One problem: he murdered that Giant, and, fresh off a recent kill, still wanted me dead. Knowing I couldn't kill him, I decided to murder all of the guards in nearby Riften, instead. So yea, something along those lines. Random shit that either nobody else would think to do and/or would never happen again in another playthrough.