First, you will have to shuffle the cards and then deal them equally until all the cards in the deck are gone. Allow the players to pick up their cards and stack them in front of them face down. Also, tell the players to not to look at their cards. They only have to create a stack and place it on the table.
Designate a place for the card pile and have each player simultaneously toss a card from the top of their pile. As each player takes a card from their own pile have them keep it face down and away so they and the other players cannot see the card until it is tossed face up on the pile.
Players will continue to toss the cards at the same time, face up on the pile, until a Jack is played. At that time it is you have to Slap the Jack. The player that slaps the Jack first gets to take the entire pile and place it on the side face down.
Continue playing. Each time a Jack is slapped the winner gets to take the pile. Once cards run out from the piles, players can use their Slap Jack piles they won from slapping the Jack first.
If you run out of cards and do not have a reserve pile you are out and the other players continue until one person has won the entire deck of cards by being the quickest to Slap the Jack.