In case you haven't got the message yet, the obliques are a really important part of overall core strength, and of course your abs. The Russian Twist is another one of those exercises that works the obliques a lot, but also works all of the abs muscles.
How do you do it? Sit on your butt, and lift your upper body off of the floor. You may also choose to lift your legs of the floor or keep your heels on the floor. Keeping your chest up, lower your upper back until you feel tension in your abs. Slowly rotate from left to right, touching the fingers to the floor and turning your head to look to that side as you go. Watch the video for a demo.
Cheers Eights & Weights!