What's the oddest twist you've ever found in a game?

So, somehow today I got on to the subject of sad moments in games with the wife (also a gamer, so not utterly odd a topic), and up came this subject as a result: What's the most "twist" moment in a game that's ever utterly thrown you? As in, that moment in a game that you completely never expected and really had an impact? 
 
For me, it's got to be "A Christmas Gift" in Elite Beat Agents. Attached is a video capture someone did, right from the opening comic explanation: 
  

Revan in KOTOR and the Reapers in Mass Effect. I really didn't see those coming. Jade Empire also had a really good one, complete with dramatic DUN DUN DUUUN sound effects and fast camera cuts.

Metal Gear Solid 2, I was 13, got to just before Arsenal Gear, Snake shows up, starts being a dick and I'm like what?! Then fucking robot ninja jumps down and I'm like "OH SHIT EPIC BATTLES" then turns out Snake and Ninja are working together and they knock Raiden out so he can get captured. 
 
Least thats my memory of it lol

" Jade Empire also had a really good one, complete with dramatic DUN DUN DUUUN sound effects and fast camera cuts. "

I NEED SCISSORS, 61!

Killzone3 Spoilers

The Christmas level in Elite Beat Agents was very touching but I think the oddest twist I've seen in a game was at the end of Assassin's Creed II, I was just left sitting there thinking "What the hell was that?, although I haven't completed Brotherhood yet and I've heard the ending to that is kind of insane.

Portal when I found out there was actually a story. I thought it was just a puzzle game with no real story but when I found one of those little hideouts the survivors used with stuff wrote on the wall like "The cake is a lie" I almost shit my pants.

Bioshock. 

The ending of Jak 3, and The entire second half of the Legacy of Kain series (both of these written by Amy Hennig). 

I'm gonna say maybe Bioshock, because that was never spoiled for me. nor was I on to anything, nor was I even prepared for it. Lotta impact. Plus it made me really angry like "D'aaah XXXX I'm gonna KILL your ass".