Trick, Treat, Or Complete and Utter Annihilation
I'm always amused by the things that come across my inbox and/or browser on Halloween. For example Techrepublic is running a special article on their blog about how to build lethal weapons with basic office supplies. I suppose that would kill boredom, as well as a few annoying co-workers. I'd be curious how it would be "sold" during performance review objectives time.
Personally, I love the "prank" aspect of this holiday. I led my students on a discussion of office practical jokes one time (yes, it had academic relevance; we were discussing the elements of corporate culture). The all-time best practical joke a student shared made me laugh so hard I was almost crying. He said that a co-worker "tinkered with" the auto-correct feature in Microsoft Word on the computer of a technologically illiterate colleague. Every time this colleague would type the word "the" Microsoft would automatically change the text to "BITE ME!" Try sharing this problem with tech support.
Really, your only goal for office trickery is to keep it off your performance appraisal and under the radar of HR. Otherwise, loosen up and have a little fun today.