A thumb twirl is another type of flourish used in club juggling that has the appearance of a club spinning horizontally on top of your hand. This trick can make you look like a really good juggler even if you can't even juggle - simply twirl one club while holding the rest.
The first thing you need to know is the club spins in a horizontal plane, not vertical or diagonal.
The second thing you need to know is that you move your thumb around the club, don't move the club around your thumb.
The latter is how most people try to do this trick on their first attempt. They grab a club spin it as fast as they can then point their thumb up in the air & hold it rigidly in position. You cannot make a club stick to your thumb by using increasing amounts of force. The more force you use the faster you will lose control.
Hold one hand out in front of you with the palm facing up & your finger tips pointing forwards. Place a club into this hand so that the waist of the club sits on the base of your index finger. The handle should lie across the diagonal line running between your thumb & your palm. Loosely grip the club with your thumb, middle, ring & little fingers. Keep your index finger are extended, supporting the body of the club from underneath. The tip of your index finger should be visible on the inside of the club when viewed directly from above.
Allow your middle, ring & little fingers to let go of the club. Keeping your thumb & index finger erect simply turn your hand from palm up to palm down. As your hand turns over your thumb pushes inwards against the handle & your index finger pushes outwards against the body. Allow the club to lazily roll on the back of your thumb. When the body of the club has turned 270° & is parallel with your chest turn your hand back from palm down to palm up. You will need to tuck your index finger under the club's body as it passes. Grab the handle with your middle, ring & little fingers as it passes over your forearm to finish back in the same position you started from. That is one twirl.
As you get better at this move you will find that you don't need to turn your hand all the way over. Instead you can turn your hand 90° from palm up to palm sideways. After the club has turned 90° push down with the thumb into the handle to keep the spin going. The club will spin on top of your fist. At the same time as you turn your hand from palm sideways to palm up & tuck your index finger under the body of the club, lift your thumb back up into its extended position.
Practise single spins in each hand until your thumbs fall off. Aim to get a nice smooth twirl that spins at the same speed all the way through the move. Also try to get the club to spin as horizontally as possible. If the bulb of the club dips forward start by holding the club a little higher up the body. If you find yourself having to jerk your hand back at the end of the spin to catch the club start holding the club a little further down the handle.
When you've perfected a single spin you are ready to learn how to spin the club continuously.
Start to spin the club as normal. As the club completes its first spin keep your middle, ring & little fingers curled up out of the way under your index finger. Tuck your finger under the body as it spins past as normal then immediately bring your finger up on the inside of the body & push it into a second spin. Stop as the club completes its second spin.
Work on two spins until your thumbs fall off again. Try to get the transition from one spin to the next as smooth as possible. The club should not lose or gain any speed during the changeover.
Other than the turning motion try to keep your hand as still as possible. If you are having to move your arm to keep your hand underneath the club then you are either spinning the club too far above or below its centre of gravity. Try starting with your hand further up or down the handle until you find the correct point of balance.
Once you have mastered the transition from one spin to the next you should be able to keep going continuously. Try three in a row, then four, then just keep adding more spins.