The air inside movie theaters apparently reek of popcorn and suspense, though our noses can't exactly smell the latter. According to researchers from the Max Planck Institute for Chemistry and the Johannes Gutenberg University in Mainz, Germany, audiences exhale chemicals that can indicate whether movies are funny or exciting. The team attached a mass spectrometer to a movie theater's air duct, which measured chemicals in the air every 30 seconds. Think of it as a big breathalyzer. Thanks to that instrument, they were able to collect data from 108 screenings (and 95,000 people) of 16 movies, including The Hunger Games 2, Carrie, The Hobbit and The Secret Life of Walter Mitty.