I don't really have one but in elder scrolls my favourite one is one from Oblivion.
It is a quest where you have to stay the night with 4 people in a house and can't get out what they don't know is that you have a hidden objective and is kill everyone without them finding out that you are the murderer;
So you start of to kill someone secretely and the other 3 will be like 'their is a murderer!!' but you sweet talk them and no one expect you so you kill again someone and one of the other two left will come to you and be like 'the murderer is the argonian/khajit/dark elf!! So you kill that person together and the person who is left is so happy that you killed the murderer and your answer is......'SLASH' and kill the person while she/he is still smiling....
Oblivion surprised me more but that's also because of the time of it's release it was more of a surprise while Skyrim already showed some of it's surprises of in trailers/announcements.
