Minecraft discussions

I recently started playing on a server with some friends from school. As of today, they have owned the game for no more than 2 weeks. They built a castle - like everyone - and have been having a jolly time. After I found 40ish diamond with a friend, they got mad and went to find their own. They just found their first diamond.

I thought I'd take their newbness and see if I could have fun with it. I dug down below their castle and made a small room. In this room is a basic pulsar connected to four note boxes set to the highest note. Poor guys have no idea what it is....

 Spoiler