Only the basics, but I stuck everything down with double sided tape on one of our sales execs desk. phone receiver, (also doubles up to tape the microphone up) Note pads, mouse, dot of superglue on the pen. Doesn't sound much but when it all gets discovered at the same time we where all in stitches. We where going to call his phone and fake a customer, however a genuine enquiry beat us to it! Once the victim hit is head with the phone when the tape finally gave, he could hear the customer, but the Mic was still taped.
Once all this had happened, he had calmed a little and was going through things with the client, the PC booted up and the display had been switched to be sideways.
They left me some crab sticks in my desk for a few weeks which was nice. So I removed some vital bolts from the backs of the chairs.
I'm planning a trip to a shop soon to purchase a scary mask for the next step.... Il keep you posted.