How to crash a minecraft 1.7 server!

a friend told me (but i added some pics for help)

Just 3 steps its very easy and still not fixed:
First after you do that its IMPOSSIBLE to fix the server,
the map lost forever, even no backups can help you!

I will use 2D acsii to show this cuz TMI not updated yet!
Signs:
X - Piston
A - Air
O - Block (ANY block)
_ - Pressure Plate

First some requiments:
1. 1 Piston
2. 1 Pressure plate (Wood/Stone)
3. Any block (even dirt)

First create hole like this:






Then put piston in:




Then put any block on the piston:



Then put pressure plate on the block you did like this:




And jump on it, then bye bye server.
will be EPIC lag and the server will crash