If you have Kali linux use this blog the here's small exercise for you
we are going to execute command in the kali linux terminal that will cripple the operating system and make it hand. It will most probably work on other linux.
Warning : This code will freeze kali linux, and most probably it ill not recover from the shock. you will lose any unsaved data. You will have to restart the machine the hard way(turn of the virtual machine directly). just copy pase the code.
Step 1: open terminal in kali linux
Step 2: type this command in terminal
:(){:|:&};:
Step 3: Press Enter
Note: The machine froze right after I pressed enter. I had to power it off from virtual machine
If any type of the loss i am not responsible so try it at your risk.