The leg-spinner's prize weapon - bowled properly, a googly is almost undetectable.
A googly, or "wrong'un", is a delivery which looks like a normal leg-spinner but actually turns towards the batsmen, like an off-break, rather than away from the bat.
Unlike a normal leg-break, a googly is delivered out of the back of the hand, with the wrist 180 degrees to the ground.
Hold the ball as if you're about to bowl a normal leg-break.
The top joints of the index and middle fingers should be across the seam, with the ball resting between a bent third finger and the thumb.
At the point of release, the palm of your hand should be open upwards, towards the sky, with the back of your hand facing the batsman.
Your wrist should be 180 degrees to the ground, while the seam of the ball should point towards fine leg.
Again, it should be your third finger which does most of the work, turning the ball anti-clockwise on release.
You'll probably find it goes horribly wrong the first few times you give the googly a try, but don't give up.
As the old saying goes, practice makes perfect. Use a tennis ball to help improve the flexibility of your wrist.