Office prank 1: Autocorrect prank Effort: Medium Results: Quite annoying When your colleague leaves their desk, open Word, go to Tools, then Autocorrect. Add some stuff to the 'Replace' and 'With' boxes. For example, replace:

'Dear' with 'Yo' or 'My darling' 'Thank you' with 'Cheers mate' 'Email' with something completely irrelevant, like 'cheese' [colleague's name] with 'Miserable git' or 'Old slapper' Make sure they use Word for emails.

Office prank 2: Whistling Effort: Minimal Results: Varies according to your musical ability (or lack thereof) Whistle tunelessly every time you're in your colleague's presence. When they ask you to stop, start humming instead.

Variation: Sing songs with the wrong words and/or out of tune. Alternatively, substitute your colleague's name, preferably in a way that is offensive, doesn't make sense, and/or doesn't scan. Eg 'Oh when the Jeffrey / goes marching in / he'll eat all the biscuits / in the biscuit tin.'

Office prank 3: Display and sound settings Effort: Quite a lot Results: Very irritating When your colleague leaves their desk, go to Control Panel, and then fiddle around with their settings for maximum irritation. Suggestions:

Change their desktop background to Hello Kitty Ballerina or WWF Wrestling, depending on what is most inappropriate Adjust the screen resolution to be ridiculously huge or ludicrously small Change their sound settings so that they are greeting with irritating noises every time they do something (sounds set to opening and closing programs are generally most annoying) Extra effect: put your own sound files on their computer, or even record your own, then set them to relevant activities. Eg, when they start their computer, it plays 'What a feeling'. Turn up the volume.

Office prank 4: Stalking Effort: Minimal (provided you’re not a lazy arse) Results: Done right, this can properly creep people out Works best on colleagues with predictable habits. When you hear them coming (out of the toilet, into their office, into the tearoom etc), stand on the other side of the door - right in front of it if it opens away from you, or slightly behind it if it opens towards you. It'll make your colleague jump, especially if you are doing your 'kid from "The Shining"' face. Done repeatedly, this can become both irritating and sinister.

Office prank 5: Computer prank Effort: Medium Results: Good Choose from the following:

Pull the keyboard cord out of the back of the computer As above, but with the mouse cord Turn down the monitor contrast until it's completely black (they'll think the monitor's broken) Swap keys around on the keyboard Risk: Someone might get paid to fix it. Unless that's you, fess up to the prank before they call in the computer experts.

Office prank 6: Phone prank Effort: Minimal (if you can get colleagues to join in) Results: Average (higher if you choose a busy department to do this to) Requires the rest of your department

Select a department to play this on. Each of your colleagues dials the extension number of one person in that department, except the last digit. At the assigned moment, all dial the last digit, making all the phones in your chosen department ring simultaneously, then hang up. Do on a regular basis for maximum irritation. Stop before someone calls in the telephone engineer.

Office prank 7: Smells Effort: Medium to high, depending on how much pongy food you have in Results: Average Microwave a tuna sandwich. Eat it at your desk.

Variations:

Hide scampi flavour crisps around your colleague's desk Put banana skins, prawn shells or boiled eggs in their bin. Tape something perishable to the underside of their desk. Allow to go off. Go to your local Asian supermarket and buy a durian (it's a fruit that smells of rotting fish and is so disgusting it is banned by many public buildings in Asia). Hide it in a cupboard. Office prank 8: Furniture Effort: Requires commitment Results: Good Lower or raise their swivel chair each time they leave their desk. Alternatively, wedge something under one leg of the desk.

Ridiculously obsessive version: After everyone has gone home, remove everything on their desk, sand down each leg a couple of millimetres, and replace everything. Do daily for several months.

Office prank 9: The internet Effort: Minimal Results: Average to good, depending on presence of boss When your colleague is away from their desk, fire up Google and switch off safe search. Type in 'fat naked people'. Click 'images'.

Works best when: the boss is accompanying your colleague back to his or her desk.

Variations: Do a normal Google search for 'how to kill boss', '[name of colleague] is a git', or 'bestiality cure'.

Office prank 10: Email prank Effort: Medium Results: Excellent Send an email from your colleague to the whole company. You can either do this from their desk, or you can fake the 'From' field in your own email account. Suggested topics:

Request for tips on how to deal with an embarrassing medical condition An apology for that nasty smell in the toilets Coming out (if your colleague is already openly gay, announce that they've gone 'back to the path of righteousness', and include a dating invitation to all single staff members of the opposite sex) Variation: a series of increasingly stupid emails, eg:

"Has anyone got some bread I can borrow?" "Does anyone have a bit of cheese or ham I could have?" "If you're passing the kitchen, would you mind bringing me a plate?" Office prank 11: Ringing phone Effort: Minimal Results: Good (better if they’re waiting for an important call) Stick a bit of card in your colleague's phone button underneath the receiver and ring them. When they go to pick the phone up and talk into it, it will still be ringing. (Thanks to Jamie Broderick.)

Office prank 12: Water water everywhere Effort: High Results: Excellent Take a bunch (20 or so) of little paper cups and fill them with water. Organise them on your colleague's desk in a straight line. Then staple them all together at the top of the cups. Watch as he/she tries to figure out how to take them off of the desk without spilling everywhere. (Thanks to James Kearns.)