Imagine presenting a blank business card with a QR code to your spectator.
They choose a celebrity, a country, an animal or a movie... You, then show a QR code and ask the spectator to scan it with their phone to reveal the prediction, their thought! The spectator tries to scan the QR code, but it doesn't work- the QR code isn't recognized by their phone. You then reveal that today, QR codes aren't flashed with a phone but with a lighter! Lighting the lighter and bringing it close to the QR code, it visually transforms, and some pixels rearrange to reveal the spectator's thought.
Extremely visual and very easy to use!