Crashing your system!
Do not run this command unless you are prepared for a system crash! This command is called as a forkbomb. Only type this in a terminal if you are prepared for a crash. It's better to try it in a virtual machine: :(){ :|: & };: :() defines a function called : {:|: &}; means run the function : and send its output to the : function again and run that in the background. This function will run again and again until you run out of system resources and this forces your computer to restart.