Parasite
Going into this movie blind was crazy.
I knew that this movie is highly rated and had to deal with the rich and poor. Based on the beginning, I thought it would just be psychological- was not expecting the garden murder scene at all. But I did expect one of the workers they got fired would come back for revenge and possibly kill them or something (but I always jump to the extreme so I wasn't expecting to be right).
Also that ending- I really thought the son's letter actually happened and they made it- but leaving it off as his desire for the future made it better.