Evil Office Pranks

Hmm,
How far is too far?
Do practical jokes have a place at work?
Improved Physical Security v0.1
A colleague has left for a break, a holiday perhaps. So why not improve the security of his PC?
Physical security is often overlooked in the office environment, trusting solely to the protection offered by having a ninja receptionist. But this can prove to be insufficient!
Adding a physical security layer to your colleagues system whilst they are away will dramatically decrease the chance of the system becoming compromised by an opportunistic malcontent, taking advantage of the ninja receptionists biannual convenience break.
Level 1: Obfuscated Keyboard
Here, intelligence agency level PET wrapping is used to provide both visual and tactile mitigation against attack.

The addition of sticky tape once the initial wrapper is attached is defined as a delay tactic as it does not in and of itself improve the security. Any malcontent attempting to bypass your Obfuscated Keyboard will need to take additional time to remove this layer before attempting the hack proper.
Level 2: Diversion
Here the addition of random elements have provided a distraction to the Level 1 security. The addition of manual writing implements, again secured with sticky tape, provides enough distraction to confuse the malcontent from their primary goal.

They may even misunderstand the task before them and attempt to disentangle every element before going for the primary target.
Level 3: Indirect Input Security
The mouse obviously allows an indirect bypass to your Obfuscated Keyboard. Therefore Special Measures must be deployed.
Level 3.1: Obfuscated Mouse
The same principle is applied here as with the Obfuscated Keyboard.

Level 3.2: Armoured Mouse
Alas due to the mechanisms used in a Mouse Obfuscation may not be enough. It is recommended that an intelligence grade PET or similar inflexible plastic confectionary container is applied. All of these will need adjusting at the top unless the Obfuscated Mouse is designed to work wirelessly.

Again ensure that the correct level of sticky tape is applied to ensure security.
Level 4: Denormalisation
One final and optional item is to remove even the Obsfucated/Diverted Keyboard from the bounds of normality.

Here, again secured using the ever trusty sticky tape, we see utilised an energy drink. Although the intelligent agencies do not endorse a particular style or brand they advise against the use of alcoholic beverages ad these may breach local regulations.
Summary:
It is absolutely guaranteed that your colleague will appreciate all your efforts in ensuring they are not the unwitting victim of a drive-by physical hack.
So much so they are likely to return the favour very quickly afterwards.
Any other business?
Do you know of a good practicale joke played at work? Let me know.