In order to do the "Whoops You Missed It" magic trick, you will need a deck of cards. Hold the deck in one hand. Rifle your way down the deck, asking the bystander to tell you where to stop in the deck. Pull out 2 cards, disguising them as one card. Turn it face up and place it on the top of the deck. Explain to the bystander, "This is your card".
Flip the deck over. Use your fingers to move the top card to the bottom. Place the Top card on the bottom. Tell them that you are going to flip over the card. Cut the deck in half. Peel and flip the deck, in order to disguise the fact that you've placed the cards upside down. Move the card to the top, as you show them that their card is not on the bottom anymore. You can choose which reveal you want to make, whether it is the card in the middle of the deck or the card that is now at the top of the deck.