Don't use root privileges without knowing what you do!!!

Just wanna share this experience:
A friend of mine asked me to install Ubuntu on his server, he took it home and turn it on... Woked well, a couple of days later, he gave me a call, asked me if I changed the password that we agreed on upon the installation and we tested it several times, I replied: I haven't!!!
You got the message guys?

Don't use root privileges without knowing what you do!!!