We filled one of our medics locker full of packing peanuts and then shut and locked it. He did not open his locker for about 3 weeks, early one morning after a long trip. I was told it looked like it was snowing when he opened it. JP

We had a guy get divorced and on the day he finalized, he arrived to find his office filled to the ceiling tiles with inflated condoms. Some we filled with sparkle confetti and inflated them up to the point they popped easily.

It was easier for us, we pulled a piece of glass to drop them in. thereby keeping the door shut. We used the shop compressor to fill them. Condoms blow up pretty darn big too...

I think I would avoid the or any other food stuff - to easy to attract unwanted pests.

I've seen taping things down (or up) like staplers, mouse, the part of the phone so when you pick up the phone it doesn't work. I've also seen post it notes everywhere, over everything. And of course, from Jim, gift wrapping everything on his desk, including his desk.

Go get 50 crickets from the pet store and turn them loose in the office.

Open up the handset on his phone and put a bunch of BBs or plastic pellets inside.

Open can of sardines hidden somewhere in the office.

Change all of his light bulbs to black lights.

I'll think of more.

You could park your Bronco on top of his car.

Well you could always make use of the train horn when he comes in - hung over and exhausted from Vegas (nobody ever came home from a Vegas vacation "refreshed" did they) Set it up under his desk with an air tank, remote switch and just about the time he thinks all is calm - let r rip

A little on the nicer side; recreate his whole office, computer and all, with cardboard. Or wrap everything in aluminum foil.

Fasten saran wrap about head level on his door frame. Walk right into it.