A great gag deck made of iron cards that seem to weigh a “ton” (actually 620g) – a deck of cards that will knock ’em dead! Switch this in for a regular deck you have just performed or played with, and ask someone to shuffle the deck.
Most likely they will just drop it with a thump! Leave the deck around in your home, as a paperweight or decorative item. Or use it to perform an ambitious card routine, with a “heavy” climax. With instructions and routine.