It's your day to be cranky so please don't mess it up for all of us by being nice or helpful. Remember to not say thank you to anyone today. Please make sure also not to hold the door for someone. Oh, and if you happen to meet a co-worker, silently walk past them with your head down. Go into someone's office and say, "Hm... smells like a dead cat in here."
If someone asks you for something, just tell them to send you an email. Make sure you turn the thermostat up as high as possible. If someone complains that it's hot, say, "I feel fine." Ask people what their problem is. Spill some coffee on the counter and don't clean it up. Leave the kitchen in an untidy state. Slam your door every time you leave the office so the walls shake. Turn you phone's ringer up as high as it will go so the sound blasts across the room every time your phone rings, and then don't answer it and let it go to voicemail. Make lots of phone calls to other people but make sure only to leave very very long voicemail messages, at least two minutes. Then when they call you back, don't answer the phone. As soon as you see the message light go off on your phone, pick it up and check your voicemail. Then call them back next week when you're less cranky.
Oh, and if someone expresses anything in their manner other than extreme positiveness and perkiness, turn on them and demand, "What the hell's the matter with you? Sheeesh! Is everything really soooo bad?"