1. Class Clown:
Do spend enough of your time goofing off that none of your coworkers can take you too seriously. Study your coworkers so you can impersonate them.

Bonus points for pulling pranks that interfere with your coworkers’ (tenuous) sanity.

2. Dress for Success:
To complete the picture of a disaffected slacker who is in no way a threat to coworkers or their aspirations of corporate ladder-climbing, sport a longish, messy haircut and make funny faces a lot.

Never wear a suit jacket, roll up your sleeves, and allow your tie to remain askew all day.

Bonus points for riding a bicycle to work and carrying the same messenger bag you bought in college.

3. Pop Culture:
Cultivate an air of mystery through the eclectic and obscure bands you listen to. Your boss will be impressed (and feel distinctly uncool) when he fails to recognize any band you mention.
However, maintain your approachability by watching reality TV so you have something to chat about with both coworkers and clients. Don’t be afraid to rent bad movies so you can bond with others about their awesome badness.

4. The Boss:
He may be the worst manager to ever walk the planet, but there is a reason he was promoted. (Namely, corporate doesn’t have to work for him.) Allow him to think that you are friends. Laugh at his (lame) jokes, and sit in stupefied silence when he says or does something completely inappropriate.

Join in his office bonding rituals, for example playing Call of Duty. Do not outshine him or your coworkers. Cultivating a reputation for befuddled, inept play will lull them into thinking you are not a threat.

Bonus points for subverting the boss's plans to humiliate innocent coworkers.

5. Motivation:
Would you rather throw yourself in front of a bus than admit that this is your career? Develop a star-crossed romance with a coworker, preferably an unavailable one. She can make your workdays both wonderful and terrible. And when she (inevitably) rejects you or marries someone else, you can apply for a promotion or transfer (preferably both) under the guise of running away from her.
As long as you’re climbing the corporate ladder away from her, you can continue to pretend that you never meant to be promoted.