This pen is a good trick to play on your friends and will suprise them but if they dont know they are going to get a shock its likely that they will throw the pen in fear, causing it to break. The only way to stop your mate dropping the pen is to explain that it will shock him, which kind of defeats the purpose of the joke. However, it isnt expensive and its good fun daring each other to press the button, but dont expect it to last long enough to have to change the batteries.