In this video, Jeremy Griffith teaches a mucking technique that allows you to change a card either secretly or visually.
Mucking comes from the gambling world where card cheats would secretly swap in high value cards in order to increase their chances of winning. Magicians have adopted the technique to be used in card effects and demonstrations.
If you like Jeremy Griffith, you can learn more techniques from him here: https://courses.52kards.com/p/tools-of-the-technician
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