For this trick, you can use any deck, with more than 20 cards, which the spectator can shuffle. You will also need another card, for example the joker, or a special card in your routine. It works best with 2 spectators.
Start by taking out 20 cards of the deck. The spectators can do it too.
Then, put the joker (or another additionnal card) in these 20 cards, and shuffle it. Show now the cards to the spectators, and ask them to memorize the 2 cards next to the joker (1 card each). Each one can then cut the deck.
Next, make 2 predictions using the rest of the deck. Take out a 5 and a 6, and put these face-down on the table.
Now, while showing again the cards to the spectators, out-jog every other card. So the 1st, 3rd, 5th, ... cards should be up, and the 2nd, 4th, 6th, cards should be down. Now put the bottom cards on top of the packet. Repeat this another time, while asking the spectators to note where their cards are.
You can now take back the deck, remove the joker, and cut the deck at that location. Divide the deck into 2 piles, without dealing cards one by one !
Ask the spectators to deal cards next to each pile, while counting, and stop when they see their cards. You can finally reveal your predictions, which correspond exactly to the positions of the spectators' selected cards.