It takes a bit of experience (and some balls) to know which people to tell off - but! Never underestimate the incredible morale boost a properly crafted "fuck you" can bring to an overworked team in the heat of battle. When followed by a company happy hour, I've seen miraculous things happen.

The world is filled with quacks and assholes - as soon as your radar is tuned, you'll be able to filter the people worth keeping good relations with.