It is a fairly well-kept secret that sharpeners have a tendency to explode in a very noticeable way. However, you will be glad to hear that this is unlikely to occur with normal usage. On the other hand, if you wanted this to happen, there is a way...

DO NOT TRY THIS AT HOME. PERFORM THIS EXPERIMENT IN A CONTROLLED ENVIRONMENT, LIKE A LAB. GET A SCIENCE TEACHER, LAB ASSISTANT OR SOMEONE WHO KNOWS WHAT THEY ARE DOING TO ASSIST YOU.

Aim:

To make a sharpener explode.

Apparatus:

• Bunsen Burner (x2)
• Tripod
• Wire Gauze
• Conical Flask
• Iron Wire
• Sharperner (make sure it is a traditional silver-looking one and not a plastic one)
• Pencil

Method:

• For safety, this experiment should be done in a fume cupboard.
• Pour water into the conical flask to a height of about 2 cm and boil over a Bunsen Burner.
• While waiting for the water to boil, tie the iron wire to the sharpener and the other end of the wire to the pencil (no, you don't need to write anything) so that the sharpener hangs 2 - 3 cm below.
• When the water is boiling, heat the sharpener above the second Bunsen Burner until it turns red.
• Drop the sharpener into the conical flask (the pencil should rest on top of the flask so that the sharpener hangs in the neck.
• Step back and close the window to the fume cupboard.
• Give it a moment...

Results:

The sharpener combusts with a bright white light. Do not stare at this light; it can damage your eyes.

Conclusion:

This one's for you to fill in... extra credit if you vote for this post!

P.S. Sorry I don't have any pictures. If anyone tries it, please post some.

P.P.S. You may want to get a couple of sharpeners since you will want to do it again.