3 senses are involved when you take a quarter and SLAP it right through the bottom of a starbucks cup.. WHILE THEY HOLD THE CUP.
1. SOUND: They can actually HEAR the coin jump into the cup.
2. FEEL: They can FEEL the moment it happens!
3. SIGHT: THEY open up the cup, and THEY take it out.
EVERYTHING is totally examinable, and by the time they open it, there's nothing to find.