This method is great to use anytime, and the spectator/shuffler has no clue what's going on. Even
better, you let them shuffle themselves and it's a convincer. Gotten some great reactions from this.
Be warned, they person shuffling needs to know how to riffle shuffle. Other than that, all
good. I've had a few that didn't know how, and I just shuffled for them. It's all good as they see
what's going on the whole time and you're turned around.