I read about this when I was very young and the effect still amazes me until now.

The elbow trick

  1. Stand in front of a wall with your hand stretched.
  2. Move forward/backwards until you are just touching the wall with your middle finger.
  3. Make sure you are upright, and not bending forward or backward.
  4. Now relax your arm and give your elbows a massage of about 30 seconds.
  5. Stretch your arm and try to reach the wall.

Awesome? Of course.
Useful? Maybe, if you want to stop being able to masturbate.