You take out one business card for every person in the group. You then turn to the first of them and ask them to think of their star sign. Before they even say ANYTHING, you write down your prediction on a card. Then, moving on to the next person you repeat this process, again writing your prediction before they say anything out loud.
Once you’ve written a prediction for everyone involved, the stack of predictions are passed around so that everyone can take the card you wrote for them. On the count of three, everyone turns their card face up and sees that not only did you correctly predict their star sign, but everyone else’s star sign too!