When we discovered our manager, Joe, had a birthday over the weekend, we celebrated by covering every item in his cubicle in tin foil. When Joe came in on monday he was much amused (and was searching for his sunglasses)
We started by covering the computer monitor and small desk items with the foil, though now we know this made things tougher later on when we tried to cover the items underneath those (i.e. the desk.) So, yeah, cover the desk first. The foil is surprisingly easy to mold to nearly all office items. The chairs and cabinets were a little more tough, but persevered since success for these kinds of pranks are 80% thoroughness/attention to detail. And these pranksters never settle for 2nd best.
Favorite items to tin foil: phone cord (it molded so nicely and you could still see the spirals underneath,) commemorative baseball cap and stand (doing them separately and then putting them back in place has a nice effect,) and papers that were held by magnets to the white board (dont be lazy and do it all in one - wrapping each piece separately is well worth the extra effort.)
Detail is key in this one - while wrapping each individual computer cord in foil sounds about as fun as giving your mother-in-law a foot massage, the attention to these small items will be much appreciated.
We've called this prank by a few names, including Aluminum Foil Office, Office of the Future, and Blindingly Awesome Office, but my favorite is Operation Tin Man.
Luckily, Joe enjoyed this prank, and he de-molded his monitor and keyboard carefully to preserve the foil in their molded shape. Pranks where you can have long-lasting remnants are extra special.