"I'm going to ask you to do something — don't worry, nothing bad — but I want you to listen to what I ask and then just do it, without thinking, as best you can. Ready?"
"Say any five-to-ten letter word — now!"
(They say a word. Repeat it aloud as you secretly record it.)
"OK, perfect — [word]. You did that pretty quickly and without thinking too much. That's important, because that gap between conscious thought and subconscious activity is where the real you lives. It's where we all live — but we never consciously spend any time there.
Have you ever had one of those weird déjà vu experiences?"
(Let them answer briefly)
"Well, that's exactly where it comes from — and that's how mind reading works. When there's a strong enough signal coming from someone, regardless of distance, mind readers have trained themselves to tune in and listen in that unconscious place. Just like you did, just now, without even realising it."
(Reveal the card)
Tips: The déjà vu question buys ~5 seconds while they respond. "Just like you did, just now" is your cue line — pause dramatically, then reveal. If the device finishes early (you feel the ringtone buzz), cut straight to the cue line from wherever you are.