I had to google this one:
1. Make sure you have a deck of cards.
2. Make a circle alternating boy-girl-boy-girl (or boy-boy or girl-girl depending on sexual orientation).
3. Pick one person to start with one card.
4. Pass the card around the circle. The first person sucks on the card (so that it is in front of their mouth, not actually in their mouth) then leans over to the next person in the circle. The next person start sucking on the card and the first person blows.
5. Continue passing the card around the circle until someone loses suction and drops the card. When this happens, the last two people to pass (the person who dropped it and the person who passed it to them) must kiss. Once they have kissed, the game continues on.
OR.....
Suck and Blow is the Next Generation of Shots and is the hottest new sensation that is sweeping the nation. Fun and EXTREMELY interactive, Suck and Blow is quickly becoming the favorite way to enjoy a gelatin shooter. Why is it so much fun? Well, Suck and Blow is a gelatin shooter encased in a patented plastic tube and in order to enjoy this flirtatious shot, you'll need a partner. That's right, it takes two to tango with this tasty treat. One person to Suck and another to Blow. It is the interaction of two people that make it so popular.