OMG!!! This is the best post EVER!! I am jealous that you are doing this and that I'm not in on it! However, we have pulled some serious doozies on numerous people where I work. Thank God I work in an environment where humor can be appreciated and that people are good sports. Here's a few good ones that my co-workers thoroughly enjoyed.....
1. We made a life-sized replica of our boss out of crumpled newspaper and duct tape. We even put clothes on his amd glasses too. We sat him at his desk and put empty beer cans, wine bottles, and other interesting things all over the place. On a note-pad infront of him we put THINGS TO DO...give the warehouse a raise, send all the admins for a spa day, the soda machines are now going to be free, flip-flops and shorts on all Fridays....you get the drift. He DIED! Plus...he still has his "clone" in a chair in his office. Tooooooo funnnyyy!!
2. We took cheap masking tape and taped the entire entrance and desk area of our co-worker to death! I mean it looked a spider came in and made a web of tape all over the joint! It was good.
3. We went to Costco and bought a giant bag of Charmin...like 40 rolls in it. We papered the office and left no stone unturned. The whole bag set us back $16.00 and it was well worth the YARDS of fun we had making this guy's office into Toilet Paper Town. Then we took photos of our handiwork and put them on Facebook. It was pretty great and the guy still talks about it to this day.
4. Here's one that they did to me.....somehow, someway, they took our PA system and put it on "open mike" on my phone line. Everytime I made a phone call or so much as picked up that phone, my voice was tunneling through the building. AND...they had two outside sales guys that were our customers call in and ask me horribly weird stuff on the phone. Like one of them asked me if I was going to the Gay Pride Parade this year with Shirley and if I was doing my Karaoke of Bette Midler's "Wind Beneath my Wings?" The whole office was on the floor laughing and I was trying to figure out what was wrong with the phones AND contain the conversations at the same time! HILARIOUS!!
Anyway...I hope you come up with some good stuff because I love a great office prank. Please tell us what happens because now I'm going to be dying to know! Maybe since he's getting married you can put a plastic ball & chain on his chair and decorate his office as if it was a crypt or a funeral. Go to Spencer's and get some cheap props...they have the greatest stuff on the fly!