2. Performance Issues (The Avengers)
Prior to the battle of New York at the end of the Avengers movie, Tony Stark figures out that Loki will be basing himself at the top of Stark Tower to give himself an audience. He heads there to confront the God of Mischief and tells him that he is doomed to fail, thanks to the Avengers. He then lists all of the Avengers and Loki asks him how they'll have time to fight him when they'll be too busy fighting Tony, who he then proceeds to try to mind-control using his sceptre. He places the sceptre on Tony's chest, as he has done to many others in the movie, to send its energies in to him to get him under his control. However, it hits Tony's arc reactor and doesn't work on him. As a result, Loki says "this usually works" and Tony likens the situation with being unable to perform in the bedroom by saying "well, performance issues... it's not uncommon".