Shank

The shank is probably the most destructive shot you can hit. Hitting a ball at 
a 45 degree angle is no fun at all and can become a source of embarrassment. 
A shank can be hit with any iron, but whatever the club the damage done 
cannot be easily remedied.
 
When you shank the ball the hosel or neck of the club is the first 
point of contact with the golf ball. This will be mainly because the 
club head is further away from the body at impact than it was at address, 
possible causes could be throwing your arms and club head away 
from your body on the downswing, creating an exaggerated out to in 
swing path.
 
The cure involves a one dozen box of golf balls. Place the box of balls 
as an obstacle just outside the golf ball, leaving enough room for your club 
to swing freely. Now start by pitching the ball short distances, 
hitting your object ball without disturbing the boxed set of golf balls. 
If your swing returns back to the ball on a poor swing path, both the 
obstacle of boxed balls and the object ball will both be struck.
 
Start by pitching the ball and gradually lengthen the club and swing 
until you feel comfortable hitting full iron shots.