In the movie Aliens, when Ripley said they should "take off and nuke the site from orbit", I always thought she said "nuke the site for morbid". I mean until very recently I just assumed this, and thought it meant until everything is dead. I watched it with subtitles on once and had a big WTF moment. In Conan the Barbarian, after Conan and Valeria had been captured the old king played by Max von Sydow asked them where their partner Subadai was. Valeria said something I couldn't understand, and very loudly the king said what I always thought was "a liar's Ahab!" Again, until very recently, when I decided to switch on subbies and discovered it was really "a lion ate him!" It turns out that was also what Valeria had said. He was repeating it ironically because right after she said it 2 guards brought Subadai into the throneroom. Facepalm moment.