That moment when you're trying to explain to a Marvel fan why Tony Stark's arc reactor breaks fundamental physics. Sorry to burst your superhero bubble, but you can't just create infinite energy in a palm-sized device without violating the first law of thermodynamics. Energy can't be created or destroyed, even by Robert Downey Jr.'s charisma.
The look of pure "why are you ruining this for me?" is universal. For the record, I still enjoy the movies—I just have to put my physics brain in a drawer next to my collection of shattered dreams and grant proposals.