Step 1: Dribble with the ball
Step 2: Turn with your right foot around the ball/stepover (move from inside around the ball to outside)
Step 3: Now turn with your left foot around the ball/stepover
Step 4: Hit the ball with the outside of your foot across your opponent
The best way to perform this trick is in one-on-one situations.
Arjen Robben Double Scissor Video