6 ways to crash your linux. Because it's fun and useless :)

This is the kind of topics that are completely useless, but that I like. It's probably like playing the Wii, it's useless, but you (we) like it.
Well, here are different ways to crash your linux box, some of them are well known, like the fork bomb, others are more obscure. Some are irreversible, others are just "for the session", where a simple reboot is enough.

Let's see them.

• The Fork bomb: this is a classic I shouldn't mention. Actually, it has a whole wikipedia page devoted to it.
  

   :(){ :|:& };: 

  will run your machine out of resource, unless you limit user processes in /etc/security/limits.conf.
  

• The next will overwrite your MBR with (pseudo) random data. At least you'll be sure not to boot your OS again (neither Windows).
  

  
  dd if=/dev/urandom of=/dev/sda bs=512 count=1
  

• Reading I/O ports can have some nice "side effects". Try to run this command and you'll see what I'm talking about
  

  sudo less -f /dev/port
  

  The result will be that your machine will freeze. I did not dig into that to know why it was freezing, but this is fun :).
  

• What happens when you overwrite the memory of a process ? Usually, it segfaults. You can put some fun (mess ?) in your system memory:
  

  cp /dev/zero /dev/mem

• This one became a cult, just because it probably already happened to you. You somehow make a confusion and you remove every single file on your hard drive
  

  rm -rf /*

  
  
• Finally, we could use the power of the find command, with the 'exec' argument that will execute the command that follows it. This kind of mistake can happen when you are in a hurry.
  

  
  find . -type f -name * -exec rm -f {} \;
  

  
  

Hopefully, a lot of these commands (except the fork bomb) won't damage your computer if you run them as a simple user, simply because the linux system won't let you access the file you don't have the permission on.
Obviously, if you try to write some LKM, the kernel will probably crash without your approval :P. From here, you could do whatever you want, since you are "God Almighty".

Do you know some other ways to crash your machine ? Don't hesitate to post your way in here.