Try To Mimic Me

You instruct a friend to mimic your actions as you put your hands in a position touching your nose, the friend, however, is not able to mimic the movements.

First put your right arm over your left arm and face your palms towards each other. Interlock your fingers so that your right pinky is on top and your left thumb on bottom. Bend your elbows outward and slide your hands in and up towards your nose. Point your two pointer fingers outward so that they make a 'v', and put your nose in this opening. Without removing your pointer fingers from their respective side of the nose, unlock your fingers and pull your arms apart.

If you ask someone to mimic you as you do this, they will likely fail, not being able to unlock their fingers without taking their pointer finger off their nose. The trick is that you can only do it if you interlock your fingers correctly (by putting your right hand over your left, than having the left thumb on bottom).