One that always sticks with me is from Paul Arden's 'It's Not How Good You Are, Its How Good You Want to Be: The World's Best Selling Book' is that:

Being Fired can be a positive career move. It means that you're at odds with your company and you've grown apart. (of course theres a caveat that getting fired for excessive porn consumption has nothing to do with your company. It just means you're creeeeeeeepy)